Liquid crystal display device and semiconductor device

ABSTRACT

By increasing an interval between electrodes which drives liquid crystals, a gradient of an electric field applied between the electrodes can be controlled and an optimal electric field can be applied between the electrodes. The invention includes a first electrode formed over a substrate, an insulating film formed over the substrate and the first electrode, a thin film transistor including a semiconductor film in which a source, a channel region, and a drain are formed over the insulating film, a second electrode located over the semiconductor film and the first electrode and including first opening patterns, and liquid crystals provided over the second electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/649,756, filed Jul. 14, 2017, now allowed, which is continuation ofU.S. application Ser. No. 15/047,844, filed Feb. 19, 2016, now U.S. Pat.No. 9,709,861, which is a continuation of U.S. application Ser. No.14/492,136, filed Sep. 22, 2014, now U.S. Pat. No. 9,268,188, which is acontinuation of U.S. application Ser. No. 14/013,292, filed Aug. 29,2013, now U.S. Pat. No. 8,841,671, which is a continuation of U.S.application Ser. No. 13/723,332, filed Dec. 21, 2012, now U.S. Pat. No.8,872,182, which is a continuation of U.S. application Ser. No.12/900,612, filed Oct. 8, 2010, now U.S. Pat. No. 8,338,865, which is acontinuation of U.S. application Ser. No. 11/746,377, filed May 9, 2007,now U.S. Pat. No. 7,816,682, which claims the benefit of a foreignpriority application filed in Japan as Serial No. 2006-135954 on May 16,2006, all of which are incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a semiconductor device and a liquidcrystal display device. In particular, the invention relates to asemiconductor device and a liquid crystal display device eachcontrolling liquid crystal molecules by generating an electric fieldalmost parallel to a substrate.

2. Description of the Related Art

One of technical development strategies of a liquid crystal displaydevice is widening a viewing angle. As a technique for realizing a wideviewing angle, a mode has been used in which gray scales are controlledby generating an electric field almost parallel to a substrate to moveliquid crystal molecules within a surface parallel to the substrate. IPS(In-Plane Switching) and FFS (Fringe-Field Switching) are given as sucha mode. In an FFS mode, a second electrode having an opening pattern(e.g., a pixel electrode of which a voltage is controlled per pixel) isprovided below liquid crystals, and a first electrode (e.g., a commonelectrode of which a voltage common to all pixels is supplied) isprovided below the opening pattern. An electric field is applied betweenthe pixel electrode and the common electrode, so that the liquidcrystals are controlled. Since an electric field is applied to theliquid crystals in a direction parallel to a substrate, liquid crystalmolecules can be controlled by using the electric field. That is, sinceliquid crystal molecules which are aligned in parallel to the substrate(so-called homogeneous alignment) can be controlled in a directionparallel to the substrate, a viewing angle is widened.

The first electrode (the common electrode) is formed to be in directcontact with a glass substrate, and a gate electrode in an inverselystaggered transistor is also formed to be in direct contact with theglass substrate. An insulating film functioning as a gate insulatingfilm in the inversely staggered transistor is formed to be in directcontact therewith. In addition, the second electrode (the pixelelectrode) is formed thereover (see Reference 1: Japanese PublishedPatent Application No. 2000-89255).

Alternatively, the first electrode (the common electrode) is formed tobe in direct contact with the insulating film functioning as the gateinsulating film in the inversely staggered transistor. Note that asemiconductor film, a source electrode, and a drain electrode are alsoformed to be in direct contact with the insulating film functioning asthe gate insulating film in the inversely staggered transistor. Inaddition, an insulating layer is formed to be in direct contacttherewith. Further, the second electrode (the pixel electrode) is formedthereover (see Reference 1: Japanese Published Patent Application No.2000-89255).

SUMMARY OF THE INVENTION

In the aforementioned conventional technique, electrodes which driveliquid crystals are provided with one insulating film interposedtherebetween. Therefore, even when a distance between the electrodes ismade to be increased, there has been limitation. If the thickness of theinsulating film interposed between electrodes is increased, for example,since a gate insulating film in a transistor is thickened there is anadverse effect such that current drive capability of the transistor isdecreased.

Further, optimal values for an arrangement interval and width of anopening pattern of a pixel electrode change depending on a distancebetween the pixel electrode and a common electrode. Thus, when thedistance between the pixel electrode and the common electrode cannot befreely set, the arrangement interval and width of the opening pattern ofthe pixel electrode have to be extremely limited values. Therefore, thesize and a direction of an electric field applied to liquid crystalmolecules are inadequate.

In view of the foregoing problems, it is an object of the invention toprovide a display device which can improve degree of freedom of aninterval between two electrodes of a display element and can apply anoptimal electric field between the electrodes, and a manufacturingmethod thereof.

In order to solve the aforementioned problems, a semiconductor device inaccordance with the invention includes a first electrode formed over asubstrate, a first insulating film formed over the first electrode, asemiconductor film formed over the first insulating film, a secondinsulating film formed over the semiconductor film, a conductive filmformed over the second insulating film, a third insulating film formedover the conductive film, and a second electrode formed over the thirdinsulating film and having an opening pattern.

A liquid crystal display device in accordance with the inventionincludes a first electrode formed over a substrate, a first insulatingfilm formed over the first electrode, a semiconductor film formed overthe first insulating film, a second insulating film formed over thesemiconductor film, a conductive film formed over the second insulatingfilm, a third insulating film formed over the conductive film, a secondelectrode formed over the third insulating film and having an openingpattern, and liquid crystals provided over the second electrode.

In accordance with each of the semiconductor device and the liquidcrystal display device, the first electrode is formed over thesubstrate, that is, below the semiconductor film. In addition, since thesecond electrode is provided over the conductive film (e.g., a gateelectrode or a source electrode of a transistor) and the thirdinsulating film, an interval between the first electrode and the secondelectrode can be increased compared with a conventional device. Further,even when thickness of the first insulating film is changed, it does notaffect another element such as a transistor very much. Therefore, thethickness thereof can be optionally changed, so that the intervalbetween the first electrode and the second electrode can be freely set.Accordingly, degree of freedom of the interval between the firstelectrode and the second electrode is improved. Then, a gradient of anelectric field applied between the electrodes can be controlled, sothat, for example, an electric field parallel to the substrate can beeasily increased. That is, since liquid crystal molecules which arealigned in parallel to the substrate (so-called homogeneous alignment)can be controlled in a direction parallel to the substrate in a displaydevice using liquid crystals, a viewing angle is widened by applying anoptimal electric field.

Note that the opening pattern is provided for generating an electricfield almost parallel to the substrate between the first electrode andthe second electrode. Therefore, the opening pattern can be variousshapes as log as it can generate the electric field which is almostparallel to the substrate.

Therefore, the opening pattern includes not only a closed openingpattern such as a slit but also includes a space which is locatedbetween conductor patterns and in which the conductor patterns are notformed such as a space between comb-shaped portions in a comb-shapedelectrode, for example. That is, the opening pattern may be any patternas long as a gap or an interval is provided between electrodes. The samecan be said hereinafter.

A semiconductor device in accordance with the invention includes a firstelectrode formed over a substrate, a first insulating film formed overthe first electrode, a semiconductor film formed over the firstinsulating film, a conductive film formed over the semiconductor film, asecond insulating film formed over the conductive film, and a secondelectrode formed over the second insulating film and having an openingpattern.

In accordance with each of the semiconductor device and the liquidcrystal display device, the first electrode is formed over thesubstrate, that is, below the semiconductor film. In addition, since thesecond electrode is provided over the conductive film (e.g., a sourceelectrode) and the insulating films, an interval between the firstelectrode and the second electrode can be increased compared with aconventional device. Further, even when thickness of the firstinsulating film is changed, it does not affect another element such as atransistor very much. Therefore, the thickness thereof can be optionallychanged, so that the interval between the first electrode and the secondelectrode can be freely set. Accordingly, degree of freedom of theinterval between the first electrode and the second electrode isimproved. Then, a gradient of an electric field applied between theelectrodes can be controlled, so that, for example, an electric fieldparallel to the substrate can be easily increased. That is, since liquidcrystal molecules which are aligned in parallel to the substrate(so-called homogeneous alignment) can be controlled in a directionparallel to the substrate in a display device using liquid crystals, aviewing angle is widened by applying an optimal electric field.

A semiconductor device in accordance with the invention includes a firstelectrode formed over a substrate, a first insulating film formed overthe first electrode, a conductive film formed over the first insulatingfilm, a semiconductor film formed over the conductive film, a secondinsulating film formed over the semiconductor film, and a secondelectrode formed over the second insulating film and having an openingpattern.

In accordance with each of the semiconductor device and the liquidcrystal display device, the first electrode is formed over thesubstrate, that is, below the semiconductor film and the conductive film(e.g., a gate electrode). In addition, since the second electrode isprovided over the second insulating film, an interval between the firstelectrode and the second electrode can be increased compared with aconventional device. Further, even when thickness of the secondinsulating film is changed, it does not affect another element such as atransistor very much. Therefore, the thickness thereof can be optionallychanged, so that the interval between the first electrode and the secondelectrode can be freely set. Accordingly, degree of freedom of theinterval between the first electrode and the second electrode isimproved. Then, a gradient of an electric field applied between theelectrodes can be controlled, so that, for example, of an electric fieldparallel to the substrate can be easily increased. That is, since liquidcrystal molecules which are aligned in parallel to the substrate(so-called homogeneous alignment) can be controlled in a directionparallel to the substrate in a display device using liquid crystals, aviewing angle is widened by applying an optimal electric field.

In a semiconductor device in accordance with the invention, the firstelectrode is a common electrode and the second electrode is a pixelelectrode in the aforementioned structure.

In a semiconductor device in accordance with the invention, the firstelectrode is a pixel electrode and the second electrode is a commonelectrode in the aforementioned structure.

A liquid crystal display device in accordance with the inventionincludes a first electrode formed over a substrate, a first insulatingfilm formed over the first electrode, a semiconductor film formed overthe first insulating film, a conductive film formed over thesemiconductor film, a second insulating film formed over the conductivefilm, a second electrode formed over the second insulating film andhaving an opening pattern, and liquid crystals provided over the secondelectrode.

A liquid crystal display device in accordance with the inventionincludes a first electrode formed over a substrate, a first insulatingfilm formed over the first electrode, a conductive film formed over thefirst insulating film, a semiconductor film formed over the conductivefilm, a second insulating film formed over the semiconductor film, asecond electrode formed over the second insulating film and having anopening pattern, and liquid crystals provided over the second electrode.

In a liquid crystal display device in accordance with the invention, theliquid crystals are controlled by an electric field between the firstelectrode and the second electrode in the aforementioned structure.

In a liquid crystal display device in accordance with the invention, thefirst electrode is a common electrode and the second electrode is apixel electrode in the aforementioned structure.

In a liquid crystal display device in accordance with the invention, thefirst electrode is a pixel electrode and the second electrode is acommon electrode in the aforementioned structure.

Note that various types of switches can be used as a switch shown in theinvention, and an electrical switch, a mechanical switch, or the like isgiven as an example. That is, any element can be used as long as it cancontrol a current flow, without limiting to a certain element. Forexample, it may be a transistor, a diode (e.g., a PN diode, a PIN diode,a Schottky diode, or a diode-connected transistor), or a logic circuitcombining such elements. In the case of using a transistor as a switch,the polarity (a conductivity type) of the transistor is not particularlylimited to a certain type because it operates just as a switch. However,a transistor of polarity with smaller off-current is preferably usedwhen small off-current is preferable. A transistor provided with an LDDregion, a transistor with a multi-gate structure, or the like is givenas an example of a transistor with smaller off-current. In addition, itis preferable that an N-channel transistor be used when a potential of asource electrode of the transistor operating as a switch is closer to alow-potential-side power supply (e.g., Vss, GND, or 0 V), while aP-channel transistor be used when the potential of the source electrodeis closer to a high-potential-side power supply (e.g., Vdd). This isbecause the absolute value of a gate-source voltage of the transistorcan be increased, so that the transistor can easily operate as a switch.Note that a CMOS switch may also be employed by using both N-channel andP-channel transistors. By employing the CMOS switch, the switch can beoperated appropriately even when a voltage output through the switch(i.e., an input voltage) is changed such that it becomes higher or lowerthan an output voltage. Note that although a TFT which controls a pixelelectrode, a switching element used for a driver circuit portion, or thelike can be given as the switch in the invention, the switch can also beused at another portion as long as it is a portion which is necessary tocontrol a current flow.

Note that in the invention, description “being connected” includes thecase where elements are electrically connected and the case whereelements are directly connected. Accordingly, in structures disclosed inthe invention, another element which enables an electrical connection(e.g., a switch, a transistor, a capacitor, an inductor, a resistor, ora diode) may be interposed between elements having a predeterminedconnection relation. Alternatively, the elements may be provided withoutinterposing another element therebetween. Note that the case where twoconductive films are not electrically connected without interposinganother element which enables an electrical connection therebetween isdescribed as “being directly connected”. Note also that description“being electrically connected” includes the case where elements areelectrically connected and the case where elements are directlyconnected.

Note that a display element, a display device, and a light-emittingdevice of the invention can employ various types and include variouselements. In the invention, a liquid crystal element can be used. Aliquid crystal element is an element which controls transmission ornontransmission of light by an optical modulation action of liquidcrystals and includes a pair of electrodes and liquid crystals. Displaydevices using liquid crystals element include a liquid crystal display,a transmissive liquid crystal display, a semi-transmissive liquidcrystal display, a reflective liquid crystal display, and the like. Inaddition, for example, a display medium, the contrast of which changesby an electromagnetic action, such as an EL element (an EL element meansan element including a light-emitting layer which can obtainluminescence generated by applying an electric field. Further, an ELelement includes an organic EL element, an inorganic EL element, or anEL element containing both organic and inorganic materials), anelectron-emissive element, electronic ink, a grating light valve (GLV),a plasma display panel (PDP), a digital micromirror device (DMD), apiezoelectric ceramic display, or a carbon nanotube can be included.Note that display devices using an EL element include an EL display;display devices using an electron-emissive element include a fieldemission display (FED), an SED-type flat panel display (SED:Surface-conduction Electron-emitter Display), and the like; and displaydevices using electronic ink include electronic paper.

Note that in the invention, various types of transistors can be appliedto a transistor without limiting to a certain type. Accordingly, a thinfilm transistor (TFT) using a non-single crystalline semiconductor filmtypified by amorphous silicon or polycrystalline silicon, a transistorformed by using a semiconductor substrate or an SOI substrate, a MOStransistor, a junction transistor, a bipolar transistor, a transistorusing a compound semiconductor such as ZnO or a-InGaZnO, a transistorusing an organic semiconductor or a carbon nanotube, or othertransistors can be applied. In addition, various types of substrates canbe used as a substrate over which a transistor is formed withoutlimiting to a certain type. Therefore, for example, the transistor canbe formed over a glass substrate, a plastic substrate, a papersubstrate, a cellophane substrate, a stone substrate, or the like.Further, in the case of manufacturing a reflective display, a singlecrystalline substrate or an SOI substrate can also be used. Moreover, atransistor may be formed over one substrate, and then, the transistormay be transferred to another substrate.

Note that as described above, various types of transistors can be usedfor the transistor in the invention and the transistor can be formedover various types of substrates. Accordingly, all circuits may beformed over a glass substrate or a plastic substrate. In the case ofmanufacturing a reflective display, the transistor may be formed over asingle crystalline substrate or an SOI substrate. That is, thetransistor may be formed over any substrate. By forming all of thecircuits over the same substrate, the number of component parts can bereduced to cut cost, or the number of connections to the circuitcomponents can be reduced to improve reliability. Alternatively, a partof the circuits may be formed over one substrate and another part of thecircuits may be formed over another substrate. That is, not all of thecircuits are required to be formed over the same substrate. For example,a part of the circuits may be formed with transistors over a glasssubstrate and another part of the circuits may be formed over a singlecrystalline substrate, so that an IC chip thereof may be connected tothe glass substrate by COG (Chip On Glass). Alternatively, the IC chipmay be connected to the glass substrate by TAB (Tape Automated Bonding)or a printed wiring board. By forming a part of the circuits over thesame substrate in this manner, the number of component parts can bereduced to cut cost, or the number of connections to the circuitcomponents can be reduced to improve reliability. In addition, byforming a portion with a high driving voltage or a portion with highdriving frequency, which consumes large power, over another substrate,increase in power consumption can be prevented.

A structure of a transistor can be various modes without limiting to acertain structure. For example, a multi-gate structure having two ormore gate electrodes may be used. By using the multi-gate structure,off-current can be reduced; the withstand voltage of the transistor canbe increased to improve reliability; or a drain-source current does notfluctuate very much even when a drain-source voltage fluctuates in asaturation region so that flat characteristics can be obtained. Inaddition, a structure where gate electrodes are formed over and below achannel may be used. By using the structure where gate electrodes areformed over and below the channel, a channel region is enlarged toincrease a current flowing therethrough, or a depletion layer can beeasily formed to decrease the S value. Further, a structure where a gateelectrode is formed over a channel, a structure where a gate electrodeis formed below a channel, a staggered structure, or an inverselystaggered structure may be used. Further, a channel region may bedivided into a plurality of regions and the divided regions may beconnected in parallel or in series. A source electrode or a drainelectrode may overlap with a channel (or a part of it). By using thestructure where the source electrode or the drain electrode may overlapwith the channel (or a part of it), a problem in that an electric chargeis accumulated in a part of the channel so that an operation becomesunstable can be prevented. Moreover, an LDD region may be provided. Byproviding the LDD region, off-current can be reduced and the withstandvoltage of the transistor can be increased to improve reliability, or adrain-source current does not fluctuate very much even when adrain-source voltage fluctuates in a saturation region so that flatcharacteristics can be obtained.

Note also that one pixel corresponds to one element which can controlbrightness in the invention. Therefore, for example, one pixelcorresponds to one color element and brightness is expressed with theone color element. Accordingly, in the case of a color display devicehaving color elements of R (Red), G (Green), and B (Blue), a minimumunit of an image is formed of three pixels of an R pixel, a G pixel, anda B pixel. Note that the color elements are not limited to three colors,and color elements with more than three colors may be employed. RGBW (Wmeans white), or RGB plus yellow, cyan, and/or magenta is given as anexample. Alternatively, as another example, in the case of controllingbrightness of one color element by using a plurality of regions, oneregion corresponds to one pixel. Therefore, for example, in the case ofperforming area gray scale display, a plurality of regions whichcontrols brightness are provided in each color element and gray scalesare expressed with the whole regions. In this case, one region whichcontrols brightness corresponds to one pixel. Thus, in that case, onecolor element includes a plurality of pixels. Further, in that case,regions which contribute to display may be different depending on eachpixel. Moreover, in a plurality of regions which control brightness ineach color element, that is, in a plurality of pixels which form onecolor element, a viewing angle may be increased by slightly varyingsignals supplied to the plurality of the pixels. Note that description“one pixel (for three colors)” corresponds to the case where threepixels of R, G, and B are considered as one pixel. Meanwhile,description “one pixel (for one color)” corresponds to the case where aplurality of pixels are provided for each color element and collectivelyconsidered as one pixel.

Note also that in the invention, pixels may be provided (arranged) inmatrix. Here, description that pixels are provided (arranged) in matrixincludes the case where the pixels are provided in stripes in aso-called grid pattern combining vertical stripes and lateral stripes.In addition, in the case of performing full color display with threecolor elements (e.g., RGB), dots of the three color elements may beprovided in a so-called delta pattern. Further, dots of the three colorelements may also be provided in Bayer arrangement. Note that the colorelements are not limited to three colors, and color elements with morethan three colors may be employed. RGBW (W means white), or RGB plusyellow, cyan, and/or magenta is given as an example. Moreover, the sizesof light-emitting regions may be different per color element.

A transistor is an element including at least three terminals of a gate,a drain, and a source, and includes a channel region between a drainregion and a source region. Here, since the source and the drain of thetransistor change depending on the structure, the operating condition,or the like of the transistor, it is difficult to define which is asource or a drain. Therefore, in the invention, one of regionsfunctioning as a source and a drain is described as a first terminal andthe other region is described as a second terminal.

A gate means all of or a part of a gate electrode and a gate wiring(also called a gate line, a gate signal line, or the like). A gateelectrode means a conductive film which overlaps with a semiconductorforming a channel region, an LDD (Lightly Doped Drain) region, or thelike with a gate insulating film interposed therebetween. A gate wiringmeans a wiring for connecting gate electrodes of respective pixels orfor connecting a gate electrode to another wiring.

However, there is also a portion functioning as both a gate electrodeand a gate wiring. Such a region may be called either a gate electrodeor a gate wiring. That is, there is a region in which a gate electrodeand a gate wiring cannot be clearly distinguished from each other. Forexample, in the case where a channel region is formed overlapping withan extended gate wiring, the overlapping region functions as both a gatewiring and a gate electrode. Accordingly, such a region may be calledeither a gate electrode or a gate wiring.

In addition, for example, a region formed of the same material as a gateelectrode and electrically connected to the gate electrode may also becalled a gate electrode. Similarly, a region formed of the same materialas a gate wiring and electrically connected to the gate wiring may alsobe called a gate wiring. In a strict sense, such a region does notoverlap with a channel region, or does not have a function of connectingto another gate electrode in some cases. However, there is a regionformed of the same material as a gate electrode or a gate wiring andelectrically connected to the gate electrode or the gate wiring, forreduction of manufacturing cost or steps, simplification of layout, orthe like. Accordingly, such a region may also be called either a gateelectrode or a gate wiring.

In a multi-gate transistor, for example, a gate electrode of onetransistor is often connected to a gate electrode of another transistorby using a conductive film which is formed of the same material as thegate electrode. Since such a region is a region for connecting a gateelectrode to another gate electrode, it may be called a gate wiring,while it may also be called a gate electrode because a multi-gatetransistor can be considered as one transistor. That is, a region whichis formed of the same material as a gate electrode or a gate wiring andelectrically connected thereto may be called either a gate electrode ora gate wiring. In addition, for example, a conductive film whichconnects a gate electrode and a gate wiring may also be called either agate electrode or a gate wiring.

Note that a gate terminal means a part of a region of a gate electrodeor a region which is electrically connected to a gate electrode.

Note also that a source means all of or a part of a source region, asource electrode, and a source wiring (also called a source line, asource signal line, or the like). A source region means a semiconductorregion containing a large amount of p-type impurities (e.g., boron orgallium) or n-type impurities (e.g., phosphorus or arsenic).Accordingly, a region containing a slight amount of p-type impurities orn-type impurities, namely, an LDD (Lightly Doped Drain) region is notincluded in a source region. A source electrode is a conductive layerformed of a different material from a source region, and electricallyconnected to the source region. However, a source electrode and a sourceregion are collectively called a source electrode in some cases. Asource wiring is a wiring for connecting source electrodes of pixels orfor connecting a source electrode to another wiring.

However, there is also a portion functioning as both a source electrodeand a source wiring. Such a region may be called either a sourceelectrode or a source wiring. That is, there is a region in which asource electrode and a source wiring cannot be clearly distinguishedfrom each other. For example, in the case where a source region overlapswith an extended source wiring, the overlapping region functions as botha source wiring and a source electrode. Accordingly, such a region maybe called either a source electrode or a source wiring.

In addition, a region formed of the same material as a source electrodeand electrically connected to the source electrode, or a portion forconnecting a source electrode to another source electrode may also becalled a source electrode. A portion which overlaps with a source regionmay also be called a source electrode. Similarly, a region formed of thesame material as a source wiring and electrically connected to thesource wiring may also be called a source wiring. In a strict sense,such a region does not have a function of connecting to another sourceelectrode in some cases. However, there is a region formed of the samematerial as a source electrode or a source wiring and electricallyconnected to the source electrode or the source wiring, for reduction ofmanufacturing cost or steps, simplification of layout, or the like.Accordingly, such a region may also be called either a source electrodeor a source wiring.

In addition, for example, a conductive film which connects a sourceelectrode and a source wiring may also be called either a sourceelectrode or a source wiring.

Note that a source terminal means a part of a region of a sourceelectrode or a region which is electrically connected to a sourceelectrode.

Note also that a drain means all of a drain region, a drain electrode,and a drain wiring. Words used for a drain in this specification aresimilar to those used for a source. Words used for a drain terminal arealso similar to those used for a source terminal.

Note also that in the invention, a semiconductor device means a devicehaving a circuit including a semiconductor element (e.g., a transistoror a diode). The semiconductor device may also include all devices thatcan function by utilizing semiconductor characteristics. In addition, adisplay device means a device having a display element (e.g., a liquidcrystal element or a light-emitting element). Note that the displaydevice may include a display panel itself where a plurality of pixelsincluding display elements such as liquid crystal elements or ELelements are formed over the same substrate as a peripheral drivercircuit for driving the pixels. The display device may also include aflexible printed circuit (FPC) or a printed wiring board (PWB) attachedto the display panel. Further, a light-emitting device means a displaydevice having a self-luminous display element, particularly, such as anEL element or an element used for an FED. A liquid crystal displaydevice means a display device having a liquid crystal element.

In the invention, description that an object is “formed on” or “formedover” another object does not necessarily mean that the object is indirect contact with another object. The description includes the casewhere the two objects are not in direct contact with each other, thatis, the case where another object is sandwiched therebetween.Accordingly, for example, when it is described that a layer B is formedon (or over) a layer A, it includes both of the case where the layer Bis formed in direct contact with the layer A, and the case where anotherlayer (e.g., a layer C or a layer D) is formed in direct contact withthe layer A and the layer B is formed in direct contact with the layer Cor D. Similarly, when it is described that an object is formed aboveanother object, it does not necessarily mean that the object is indirect contact with another object, and another object may be sandwichedtherebetween. Accordingly, for example, when it is described that alayer B is formed above a layer A, it includes both of the case wherethe layer B is formed in direct contact with the layer A, and the casewhere another layer (e.g., a layer C or a layer D) is formed in directcontact with the layer A and the layer B is formed in direct contactwith the layer C or D. Similarly, when it is described that an object isformed below or under another object, it includes both of the case wherethe objects are in direct contact with each other, and the case wherethe objects are not in contact with each other. Note that here when itis described that an object is formed above or over another object, asubstrate over which an electrode is formed is used as a base and a sideover which the electrode is formed corresponds to a direction describedas “above” or “over”.

By employing the invention, an interval between the first electrode andthe second electrode can be increased and controlled without affectinganother element, so that degree of freedom of the interval therebetweenis improved. Accordingly, since optimal values for an arrangementinterval and width of an opening pattern of a pixel electrode changedepending on a distance between the pixel electrode and a commonelectrode, the size, the width, and the interval of the opening patterncan also be freely set. Then, a gradient of an electric field appliedbetween the electrodes can be controlled, so that, for example, anelectric field parallel to a substrate can be easily increased. Inparticular, since liquid crystal molecules which are aligned in parallelto the substrate (so-called homogeneous alignment) can be controlled ina direction parallel to the substrate in a display device using liquidcrystals, a viewing angle is widened by applying an optimal electricfield.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 2, and FIG. 1B is across-sectional view taken along a line E-F and a line G-H in FIG. 1A;

FIG. 2A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 2, and FIG. 2B is across-sectional view taken along a line E-F and a line G-H in FIG. 2A;

FIG. 3A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 3, and FIG. 3B is across-sectional view taken along a line E-F and a line G-H in FIG. 3A;

FIG. 4A is a plan view showing a structure of an IPS-mode liquid crystaldisplay device in accordance with Embodiment Mode 4, and FIG. 4B is across-sectional view taken along a line A-B and a line C-D in FIG. 4A;

FIG. 5A is a plan view showing a structure of an IPS-mode liquid crystaldisplay device in accordance with Embodiment Mode 5, and FIG. 5B is across-sectional view taken along a line A-B and a line C-D in FIG. 5A;

FIG. 6A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 6, and FIG. 6B is across-sectional view taken along a line E-F and a line G-H in FIG. 6A;

FIG. 7A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 7, and FIG. 7B is across-sectional view taken along a line E-F and a line G-H in FIG. 7A;

FIG. 8A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 8, and FIG. 8B is across-sectional view taken along a line E-F and a line G-H in FIG. 8A;

FIG. 9A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 9, and FIG. 9B is across-sectional view taken along a line E-F and a line G-H in FIG. 9A;

FIG. 10A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 10, and FIG.10B is a cross-sectional view taken along a line E-F and a line G-H inFIG. 10A;

FIG. 11A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 11, and FIG.11B is a cross-sectional view taken along a line E-F and a line G-H inFIG. 11A;

FIG. 12A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 12, and FIG.12B is a cross-sectional view taken along a line E-F and a line G-H inFIG. 12A;

FIG. 13A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 13, and FIG.13B is a cross-sectional view taken along a line E-F and a line G-H inFIG. 13A;

FIG. 14A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 14, and FIG.14B is a cross-sectional view taken along a line E-F and a line G-H inFIG. 14A;

FIG. 15A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 15, and FIG.15B is a cross-sectional view taken along a line E-F and a line G-H inFIG. 15A;

FIG. 16A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 16, and FIG.16B is a cross-sectional view taken along a line E-F and a line G-H inFIG. 16A;

FIG. 17A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 17, and FIG.17B is a cross-sectional view taken along a line E-F, a line G-H, a lineI-J in FIG. 17A;

FIG. 18A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 18, and FIG.18B is a cross-sectional view taken along a line E-F and a line G-H inFIG. 18A;

FIG. 19A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 19, and FIG.19B is a cross-sectional view taken along a line K-L and a line I-J inFIG. 19A;

FIG. 20A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 20, and FIG.20B is a cross-sectional view taken along a line M-N and a line O-P inFIG. 20A;

FIG. 21A is a cross-sectional view showing a structure of an FFS-modeliquid crystal display device in accordance with Embodiment Mode 21, andFIG. 21B is a cross-sectional view showing a structure of an FFS-modeliquid crystal display device in accordance with Embodiment Mode 22;

FIG. 22 is a cross-sectional view showing a structure of an FFS-modeliquid crystal display device in accordance with Embodiment Mode 23;

FIG. 23 is a cross-sectional view showing a structure of a liquidcrystal display device in accordance with Embodiment Mode 24;

FIG. 24A is a plan view of the liquid crystal display device shown inFIG. 23, and FIG. 24B is an enlarged view of a pixel portion in FIG.24A;

FIG. 25A is a plan view of a liquid crystal display device in accordancewith Embodiment Mode 25, and FIG. 25B is an enlarged view of a pixelportion in FIG. 25A;

FIG. 26 is a cross-sectional view showing a structure of a liquidcrystal display device in accordance with Embodiment Mode 26;

FIGS. 27A to 27D are plan views each showing a shape of an electrode ofan FFS-mode liquid crystal display device in accordance with EmbodimentMode 27;

FIGS. 28A to 28D are plan views each showing a shape of an electrode ofan IPS-mode liquid crystal display device in accordance with EmbodimentMode 28;

FIG. 29 is a circuit diagram showing a circuit configuration of a liquidcrystal display device in accordance with Embodiment Mode 29;

FIGS. 30A and 30B are circuit diagrams each showing a circuitconfiguration of a liquid crystal display device in accordance withEmbodiment Mode 30;

FIGS. 31A to 31E are cross-sectional views showing a manufacturingmethod of a liquid crystal module in accordance with Embodiment Mode 31;

FIGS. 32A to 32D are cross-sectional views showing a manufacturingmethod of the liquid crystal module in accordance with Embodiment Mode31;

FIG. 33A is a plan view of the liquid crystal module in accordance withEmbodiment Mode 31, and FIG. 33B is a cross-sectional view taken along aline K-L in FIG. 33A;

FIGS. 34A and 34B are diagrams showing a liquid crystal display modulein accordance with Embodiment Mode 32;

FIGS. 35A and 35B are diagrams showing the liquid crystal display modulein accordance with Embodiment Mode 32;

FIGS. 36A to 36H are perspective views each showing an electronic devicein accordance with Embodiment Mode 33;

FIG. 37 is a cross-sectional view in accordance with Embodiment Mode 1,showing a basic structure of the invention; and

FIGS. 38A and 38B are cross-sectional views each showing a structure ofa light-emitting device in accordance with Embodiment Mode 34.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the invention is described by way of embodiment modes withreference to the drawings. However, the invention can be implemented byvarious different ways and it will be understood that various changesand modifications will be apparent to those skilled in the art. Unlesssuch changes and modifications depart from the spirit and the scope ofthe invention, they should be construed as being included therein.Therefore, the invention should not be construed as being limited to thedescription of embodiment modes.

Embodiment Mode 1

FIG. 37 is a cross-sectional view showing a basic structure of theinvention. A first electrode 3701 is formed over a substrate 3700. Thesubstrate 3700 is a glass substrate, a quartz substrate, a substrateformed of an insulator such as alumina, a plastic substrate having heatresistance which can resist processing temperature of a post-process, asilicon substrate, or a metal substrate. In the case of operating as atransmissive display device, it is preferable that the substrate 3700have a light-transmitting property.

The first electrode 3701 is formed by using a conductive film whichtransmits visible light (e.g., ITO: Indium Tin Oxide).

An insulating film 3704 is formed over the substrate 3700 and the firstelectrode 3701. The insulating film 3704 is formed of an insulatingsubstance having oxygen or nitrogen such as silicon oxide (SiO_(x)),silicon nitride (SiN_(x)), silicon oxynitride (SiO_(x)N_(y):x>y), orsilicon nitride oxide (SiN_(x)O_(y):x>y), and may be a single-layerstructure of any of these films or may be a stacked-layer structure of aplurality of these films. By providing the insulating film 3704,diffusion of an impurity from the substrate 3700 to an upper layer ofthe insulating film 3704 can be prevented.

Note that a gate electrode, a gate wiring, a gate insulating film, orthe like may be further provided between the substrate 3700 and theinsulating film 3704. Out of these, for example, the gate electrodeand/or the gate wiring may be formed in the same step as the firstelectrode 3701.

A thin film transistor 3703 is formed over the insulating film 3704. Thethin film transistor 3703 may be either a top-gate thin film transistoror a bottom-gate thin film transistor. The thin film transistor 3703 isprovided around the first electrode 3701 and a second electrode 3702.

An interlayer insulating film 3705 is formed over the thin filmtransistor 3703 and the insulating film 3704. The interlayer insulatingfilm 3705 may be a single-layer or a multi-layer structure.

An inorganic material or an organic material can be used as a materialwhich forms the interlayer insulating film 3705. As an organic material,polyimide, acryl, polyamide, polyimide amide, resist, siloxane,polysilazane, or the like can be used. As an inorganic material, aninsulating substance having oxygen or nitrogen such as silicon oxide(SiO_(x)), silicon nitride (SiN_(x)), silicon oxynitride(SiO_(x)N_(y):x>y), or silicon nitride oxide (SiN_(x)O_(y):x>y) can beused. In addition, a stacked-layer film of a plurality of these filmsmay be used. Further, a stacked-layer film may also be used by combiningan organic material and an inorganic material.

In the case of using an inorganic material for the interlayer insulatingfilm 3705, penetration of moisture or an impurity can be prevented. Inparticular, a function of blocking moisture or an impurity is high whena layer including nitrogen is used. Alternatively, in the case of usingan organic material for the interlayer insulating film 3705, a surfacethereof can be flattened. Therefore, an advantageous effect can beproduced on a layer formed thereover. For example, since a layer formedover the organic material can also be flattened, random orientation ofliquid crystals can be prevented, disconnection of a wiring can beprevented, and resist can be formed precisely.

The second electrode 3702 is formed over the interlayer insulating film3705. It is preferable that a material having a high light-transmittingproperty be used for the second electrode 3702. For example, it ispreferable to use one element or a plurality of elements selected from agroup of indium (In), tin (Sn), and oxygen (O), or a compound and analloy material including one element or a plurality of elements selectedfrom the group as a component (e.g., Indium Tin Oxide (ITO), Indium ZincOxide (IZO), or Indium Tin Oxide to which silicon oxide is added(ITSO)). IZO is particularly preferable because it can be easilyprocessed and can be formed minutely with a precise shape. However, theinvention is not limited to this.

One of the first electrode 3701 and the second electrode 3702 functionsas an electrode to which a signal which is different depending on apixel is supplied in accordance with a video signal, that is, aso-called pixel electrode, and is electrically connected to a source ora drain of the thin film transistor 3703. In addition the other of thefirst electrode 3701 and the second electrode 3702 functions as a commonelectrode.

An opening pattern (a slit) is formed in the second electrode 3702. Thisopening pattern is provided for generating an electric field which isalmost parallel to the substrate between the first electrode 3701 andthe second electrode 3702. The opening pattern can be various shapes aslog as it can generate an electric field having a part which is almostparallel to the substrate. Here, description “almost parallel”corresponds to the case where two objects are in parallel to each otherwith a little deviation. Accordingly, two objects may be deviated from aparallel direction as long as it does not affect display. For example,the description “almost parallel” includes the case of having adeviation of ±10 degrees, and more preferably, the case of having adeviation of around ±5 degrees.

Therefore, the opening pattern includes not only a closed openingpattern such as a slit but also includes a space which is locatedbetween conductor patterns and in which the conductor patterns are notformed such as a space between comb-shaped portions in a comb-shapedelectrode, for example. That is, the opening pattern may be any patternas long as a gap or an interval is provided between electrodes.

By generating an electric field between the second electrode 3702 andthe first electrode 3701 in this manner, an orientation state of liquidcrystal molecules can be controlled.

As described above, the insulating film 3704 is located between thefirst electrode 3701 and the thin film transistor 3703 in thisembodiment mode. Thus, by controlling thickness of the insulating film3704, degree of freedom of an interval between the first electrode 3701and the second electrode 3702 is improved. Accordingly, since optimalvalues for an arrangement interval and width of the opening pattern ofthe pixel electrode change depending on a distance between the pixelelectrode and the common electrode, the size, the width, and theinterval of the opening pattern can be freely set. Then, a gradient ofan electric field applied between the electrodes can be controlled, sothat, for example, an electric field parallel to the substrate can beeasily increased. That is, since liquid crystal molecules which arealigned in parallel to the substrate (so-called homogeneous alignment)can be controlled in a direction parallel to the substrate in a displaydevice using liquid crystals, a viewing angle is widened by applying anoptimal electric field.

In addition, an operation or the like of the transistor is not affectedeven when thickness of the insulating film 3704 is changed, so that thethickness thereof can be freely controlled. Therefore, the intervalbetween the first electrode 3701 and the second electrode 3702 can befreely increased.

Note that although only second electrode 3702 has the opening pattern inFIG. 37, the first electrode 3701 may also have an opening pattern.Thus, the electric field almost parallel to the substrate is generated,so that the liquid crystal molecules can be controlled.

Further, unless transmittance is 100%, the amount of light transmissiondecreases when the first electrode 3701 is provided. However, when anopening pattern is provided in the first electrode 3701, light does notattenuate in a portion of the opening pattern, and thus, the amount oflight transmission increases as a whole. Accordingly, luminance can beimproved and power consumption can be reduced.

Embodiment Mode 2

FIG. 1A is a plan view showing a structure of a liquid crystal displaydevice in accordance with Embodiment Mode 2 of the invention. A pixelfor one pixel is shown. This liquid crystal display device is a devicewhich controls an alignment direction of liquid crystals by an FFS-mode.In FIG. 1A, a plurality of source wirings 108 are provided in parallelwith each other (extended in a longitudinal direction in the drawing)and separated from each other. A plurality of gate wirings 105 areprovided so as to be extended in a direction which is almostperpendicular to the source wirings 108 (in a horizontal direction inthe drawing) and separated from each other. Auxiliary wirings 106 areprovided in positions adjacent to each of the plurality of gate wirings105, and extended in a direction which is almost parallel to the gatewirings 105, that is, in a direction which is almost perpendicular tothe source wirings 108 (in the horizontal direction in the drawing).Almost rectangular space is surrounded by the source wirings 108, theauxiliary wirings 106, and the gate wirings 105, and a pixel electrodeof the liquid crystal display device is provided in this space. A thinfilm transistor 121 for driving the pixel electrode is provided on anupper left corner in the drawing. A plurality of pixel electrodes andthin film transistors are provided in matrix.

Note that each of the gate wiring 105, the auxiliary wiring 106, and thesource wiring 108 is formed to have one element or a plurality ofelements selected from a group of aluminum (Al), tantalum (Ta), titanium(Ti), molybdenum (Mo), tungsten (W), neodymium (Nd), chromium (Cr),nickel (Ni), platinum (Pt), gold (Au), silver (Ag), copper (Cu),magnesium (Mg), scandium (Sc), cobalt (Co), zinc (Zn), niobium (Nb),silicon (Si), phosphorus (P), boron (B), arsenic (As), gallium (Ga),indium (In), tin (Sn), and oxygen (O), a compound or an alloy materialincluding one or a plurality of the elements selected from the group asa component (e.g., Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO),Indium Tin Oxide to which silicon oxide is added (ITSO), zinc oxide(ZnO), aluminum neodymium (Al—Nd), or magnesium silver (Mg—Ag)), asubstance in which these compounds are combined, or the like.Alternatively, each of the gate wiring 105, the auxiliary wiring 106,and the source wiring 108 is formed to have a compound of silicon andthe above-described material (silicide) (e.g., aluminum silicon,molybdenum silicon, or nickel silicide) or a compound of nitrogen andthe above-described material (e.g., titanium nitride, tantalum nitride,or molybdenum nitride). Note also that a large amount of n-typeimpurities (e.g., phosphorus) or p-type impurities (e.g., boron) may beincluded in silicon (Si). By including the impurities, conductivity isimproved and behavior similar to a normal conductor is exhibited, sothat each of the gate wiring 105, the auxiliary wiring 106, and thesource wiring 108 can be easily utilized as a wiring or an electrode.Silicon may be single crystalline silicon, polycrystalline silicon(polysilicon), or amorphous silicon. By using single crystalline siliconor polycrystalline silicon, resistance can be reduced. By usingamorphous silicon, it can be manufactured with a simple manufacturingprocess. Since aluminum or silver has high conductivity, signal delaycan be reduced. In addition, aluminum or silver is easily etched andpatterned, so that minute processing can be performed. Since copper hashigh conductivity, signal delay can be reduced. Molybdenum is preferablebecause it can be manufactured without generating a problem that amaterial causes a defect even when molybdenum is in contact withsemiconductor oxide such as ITO or IZO or silicon, patterning andetching are easily performed, and heat resistance is high. Titanium ispreferable because it can be manufactured without generating a problemthat a material causes a defect even when titanium is in contact withsemiconductor oxide such as ITO or IZO or silicon, and heat resistanceis high. Tungsten is preferable because heat resistance is high.Neodymium is preferable because heat resistance is high. In particular,it is preferable to use an alloy of neodymium and aluminum because heatresistance is improved and a hillock is hardly generated in aluminum.Silicon is preferable because it can be formed at the same time as asemiconductor film included in a transistor and heat resistance is high.Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Indium Tin Oxide towhich silicon oxide is added (ITSO), zinc oxide (ZnO), and silicon (Si)are preferable because these materials have light-transmittingproperties and can be used for a portion which transmits light. Forexample, these materials can be used for a pixel electrode or a commonelectrode.

Note that a wiring or an electrode may be formed of the above-describedmaterial with a single-layer structure or a multi-layer structure. Byforming the wiring or the electrode with a single-layer structure, amanufacturing process can be simplified; the number of days for aprocess can be reduced; and cost can be reduced. Alternatively, byforming the wiring or the electrode with a multi-layer structure, anadvantage of each material is taken and a disadvantage thereof isreduced so that a wiring or an electrode with high performance can beformed. For example, by including a material with low resistance (e.g.,aluminum) in a multi-layer structure, resistance in the wiring can bereduced. In addition, by including a material with high heat resistance,for example, by employing a stacked-layer structure in which a materialwith low heat resistance and having a different advantage is sandwichedwith materials with high heat resistance, heat resistance in the wiringor the electrode as a whole can be improved. For example, it ispreferable that a stacked-layer structure be employed in which a layerincluding aluminum is sandwiched with layers including molybdenum ortitanium. Further, when there is a portion which is in direct contactwith a wiring, an electrode, or the like formed of another material,they may be adversely affected each other. For example, in some cases,one material enters the other material and changes property thereof, sothat an original purpose cannot be achieved; there occurs a problem inmanufacturing, so that normal manufacturing cannot be performed. In sucha case, by sandwiching or covering a certain layer with differentlayers, the problem can be solved. For example, when Indium Tin Oxide(ITO) is to be in contact with aluminum, it is preferable to interposetitanium or molybdenum therebetween. Moreover, when silicon is to be incontact with aluminum, it is preferable to interpose titanium ormolybdenum therebetween.

It is preferable that a material with heat resistance higher than thatof a material used for the source wiring 108 be used for the gate wiring105. This is because the gate wiring 105 is often disposed in ahigher-temperature state in a manufacturing process.

It is preferable that a material with resistance lower than that of amaterial used for the gate wiring 105 be used for the source wiring 108.This is because although only a signal of a binary value of an H signaland an L signal is supplied to the gate wiring 105, an analog signal issupplied to the source wiring 108 to contribute to display. Therefore,it is preferable to use a material with low resistance for the sourcewiring 108 so as to supply an accurate signal.

Although the auxiliary wiring 106 is not necessarily provided, apotential of a common electrode in each pixel can be stabilized byproviding the auxiliary wiring 106. Note that although the auxiliarywiring 106 is provided in almost parallel to a gate line in FIG. 1A, theinvention is not limited to this. The auxiliary wiring 106 may beprovided in almost parallel to the source wiring 108. At that time, theauxiliary wiring 106 is preferably formed of the same material as thesource wiring 108.

Note that the auxiliary wiring 106 is preferably provided in almostparallel to the gate line because an aperture ratio can be increased andlayout can be efficiently performed.

FIG. 1B is a cross-sectional view taken along a line E-F and a line G-Hin FIG. 1A. As shown in FIG. 1B and FIG. 1A, a first electrode 101 whichcontrols an alignment direction of liquid crystals is provided over apart of a substrate 100. Note that another layer may be provided betweenthe substrate 100 and the first electrode 101.

The substrate 100 is a glass substrate, a quartz substrate, a substrateformed of an insulator such as alumina, a plastic substrate having heatresistance that can resist processing temperature of a post-process, asilicon substrate, or a metal substrate. Alternatively, the substrate100 may be polysilicon.

In the case of operating as a transmissive display device, it ispreferable that the substrate 100 have a light-transmitting property.

The first electrode 101 is formed of a conductive film having alight-transmitting property (e.g., an ITO (Indium Tin Oxide) film, anIZO (Indium Zinc Oxide) film, a ZnO film, a polysilicon film or anamorphous silicon film into which an impurity is introduced), andfunctions as a common electrode. As shown in FIG. 1A, the firstelectrode 101 is connected up and down. By connecting in this manner,resistance of the common electrode is reduced and a predeterminedvoltage can be easily applied to the first electrode 101.

An insulating film 102 is formed over the first electrode 101 and thesubstrate 100. The insulating film 102 is a film for preventingdiffusion of an impurity from the substrate 100 and functions as a basefilm. The insulating film 102 is formed of an insulating substancehaving oxygen or nitrogen such as silicon oxide (SiO_(x)), siliconnitride (SiN_(x)), silicon oxynitride (SiO_(x)N_(y):x>y), or siliconnitride oxide (SiN_(x)O_(y):x>y). In addition, the insulating film 102may be a stacked-layer film of a plurality of these films. Note that aninsulating film having the same function as the insulating film 102 maybe provided between the substrate 100 and the first electrode 101.

A semiconductor film 103 is formed over the insulating film 102. Animpurity region 103 a serving as a source of the thin film transistor121 and an impurity region 103 b serving as a drain thereof are formedin the semiconductor film 103. For example, the impurity regions 103 aand 103 b are n-type impurity regions. However, the impurity regions 103a and 103 b may be p-type impurity regions. Phosphorus (P) and arsenic(As) are given as examples of impurities which impart n-typeconductivity, and boron (B) and gallium (Ga) are given as examples ofimpurities which impart p-type conductivity.

As shown by a dotted line in FIG. 1A, the first electrode 101 has ashape of a rectangle lacking one corner (the upper left corner in thedrawing) and is formed in almost the whole area of pixels. Note that thethin film transistor 121 is provided in a portion 101 d of the lackedcorner of the rectangle. By providing the thin film transistor 121 inthis portion 101 d of the lacked corner, a region which is effective fordisplay in the pixels can be formed more efficiently. That is, thisleads to improvement of the aperture ratio. Note that although thesemiconductor film 103 is a polysilicon film, for example, it may beanother semiconductor film (e.g., an amorphous silicon film, a singlecrystalline silicon film, an organic semiconductor film, or a carbonnanotube).

A gate insulating film 104 of the thin film transistor 121 is formed soas to cover the semiconductor film 103.

Note that the gate insulating film 104 is provided only around a channelregion and is not provided in the other regions in some cases. Inaddition, thickness or a stacked-layer structure of the gate insulatingfilm 104 may be different depending on a place. For example, thethickness is thick or the number of layers is many only around thechannel region, and the thickness is thin or the number of layers is fewin the other regions in some cases. By providing the gate insulatingfilm 104 in this manner, addition of impurities to a source region and adrain region can be easily controlled. In addition, by changing thethickness or the number of layers of the gate insulating film 104 aroundthe channel region, the amount of addition of an impurity to thesemiconductor film is changed depending on a place, so that an LDDregion can be formed. By forming the LDD region, leakage current can bereduced, and generation of a hot carrier can be suppressed to improvereliability.

The gate insulating film 104 is formed of an insulating substance havingoxygen or nitrogen such as silicon oxide (SiO_(x)), silicon nitride(SiN_(x)), silicon oxynitride (SiO_(x)N_(y):x>y), or silicon nitrideoxide (SiN_(x)O_(y):x>y). In addition, the gate insulating film 104 maybe a stacked-layer film of a plurality of these films. Gate electrodes105 a and 105 b located above the semiconductor film 103 are formed overthe gate insulating film 104. As shown in FIG. 1B and FIG. 1A, each ofthe gate electrodes 105 a and 105 b is the same wiring layer as theauxiliary wiring 106 and the gate wiring 105 and electrically connectedto the gate wiring 105. The semiconductor film 103 located below each ofthe gate electrodes 105 a and 105 b functions as channel region 103 c.Impurities which are the same as those of the impurity regions 103 a and103 b are also introduced into the semiconductor film 103 locatedbetween two channel regions 103 c. Note that although a multi-gatestructure having two gate electrodes is used in this embodiment mode,the invention is not limited to this structure.

A first interlayer insulating film 107 is formed over the gateinsulating film 104 and the gate electrodes 105 a and 105 b. Aninorganic material or an organic material can be used for the firstinterlayer insulating film 107. As an organic material, polyimide,acryl, polyamide, polyimide amide, resist, siloxane, polysilazane, orthe like can be used. As an inorganic material, an insulating substancehaving oxygen or nitrogen such as silicon oxide (SiO_(x)), siliconnitride (SiN_(x)), silicon oxynitride (SiO_(x)N_(y):x>y), or siliconnitride oxide (SiN_(x)O_(y):x>y) can be used. In addition, astacked-layer film of a plurality of these films may be used. Further, astacked-layer film may be used by combining an organic material and aninorganic material. A contact hole located over the impurity region 103a, a contact hole located over the impurity region 103 b, a contact holelocated over the first electrode 101, and a contact hole located overthe auxiliary wiring 106 are formed in the insulating film 102, the gateinsulating film 104, and the first interlayer insulating film 107. Thesource wiring 108, a conductive film for connecting 109, and aconductive film for connecting 110 are formed over the first interlayerinsulating film 107.

In the case of using an inorganic material as the insulating film,penetration of moisture or an impurity can be prevented. In particular,a function of blocking moisture or an impurity is high when a layerincluding nitrogen is used.

Note that in the case of using an organic material as the insulatingfilm, a surface thereof can be flattened. Therefore, an advantageouseffect can be produced on a layer formed thereover. For example, since alayer formed over the organic material can also be flattened, randomorientation of liquid crystals can be prevented.

The source wiring 108 is located over the impurity region 103 a, and iselectrically connected to the impurity region 103 a by being partiallyembedded in the contact hole. Accordingly, a source electrode serves asa part of the source wiring 108. The conductive film for connecting 109is electrically connected to the impurity region 103 b by beingpartially embedded in the contact hole. By providing the conductive filmfor connecting 109 in this manner, the contact hole can be preciselyformed because it is not necessary to open the contact hole deeply.

Note that as shown in FIG. 2B, a second electrode 112 and the impurityregion 103 b may be directly connected without interposing theconductive film for connecting 109 shown in FIG. 1B therebetween. Inthis case, although a contact hole for connecting the second electrode112 and impurity region 103 b is required to be opened deeply, theconductive film for connecting 109 is not required so that its regioncan be utilized as an opening region for displaying an image. Therefore,the aperture ratio is improved and power consumption can be reduced.

The conductive film for connecting 110 is located over the auxiliarywiring 106, and is electrically connected to each of the auxiliarywiring 106 and the first electrode 101 by being partially embedded inthe contact hole. The first electrode 101 is electrically connected tothe auxiliary wiring 106 through the conductive film for connecting 110in this manner. Note that a plurality of conductive films for connecting110 may be provided. Thus, a potential of the first electrode 101 isstabilized. The number of times to open the contact holes can be reducedby connecting the first electrode 101 and the auxiliary wiring 106through the conductive film for connecting 110, so that process stepscan be simplified.

Note that although the conductive film for connecting 110 is formed ofthe same material and at the same time as the source wiring 108, theinvention is not limited to this. The conductive film for connecting 110may be formed of the same material and at the same time as the secondelectrode 112.

A second interlayer insulating film 111 is formed over the source wiring108, the conductive film for connecting 109, the conductive film forconnecting 110, and the first interlayer insulating film 107. Note thata structure may be used in which the second interlayer insulating film111 is not formed. An inorganic material or an organic material can beused for the second interlayer insulating film 111. As an organicmaterial, polyimide, acryl, polyamide, polyimide amide, resist,siloxane, polysilazane, or the like can be used. As an inorganicmaterial, an insulating substance having oxygen or nitrogen such assilicon oxide (SiO_(x)), silicon nitride (SiN_(x)), silicon oxynitride(SiO_(x)N_(y):x>y), or silicon nitride oxide (SiN_(x)O_(y):x>y) can beused. In addition, a stacked-layer film of a plurality of these filmsmay be used. Further, a stacked-layer film may be used by combining anorganic material and an inorganic material. A contact hole located overthe conductive film for connecting 109 is formed in the secondinterlayer insulating film 111.

The second electrode 112 which controls an alignment direction of liquidcrystals is provided over the second interlayer insulating film 111. Thesecond electrode 112 functions as a pixel electrode to which anindividual voltage depending on a pixel is supplied, and is formed ofITO (Indium Tin Oxide), ZnO (zinc oxide), IZO (Indium Zinc Oxide) whichis formed by using a target in which indium oxide is mixed with ZnO at 2to 20 wt %, or the like. The second electrode 112 is partially locatedover the conductive film for connecting 109, and is electricallyconnected to the conductive film for connecting 109 by being partiallyembedded in the contact hole. In this manner, the second electrode 112is electrically connected to the impurity region 103 b of the thin filmtransistor 121 with the conductive film for connecting 109 interposedtherebetween.

Note that as shown in FIG. 2B, when the conductive film for connecting109 is not provided, the second electrode 112 is directly connected tothe impurity region 103 b of the thin film transistor 121.

As shown in FIGS. 2A and 2B and FIG. 1A, the second electrode 112 isalmost rectangular, is located over the first electrode 101, and has aplurality of opening patterns 112 a and 112 b. Opening patterns whichare slit shapes and in parallel to each other are often included asexamples of the opening patterns 112 a and 112 b. In the example shownin this embodiment mode, although directions of the opening patterns 112a and 112 b are diagonal to the source wiring 108, a direction of theopening pattern 112 a located in a upper half of the pixel in thedrawing and a direction of the opening pattern 112 b located in a lowerhalf of the pixel in the drawing are different from each other. Byforming the opening patterns 112 a and 112 b, an electric field having acomponent which is between the first electrode 101 and the secondelectrode 112 and in parallel to the substrate is generated above thesecond electrode 112. Therefore, an alignment direction of liquidcrystals which are described later can be controlled by controlling apotential of the second electrode 112.

By providing opening patterns having different directions like theopening patterns 112 a and 112 b, a plurality of regions havingdifferent moving directions of liquid crystal molecules can also beprovided. That is, a multi-domain structure can be formed. By employinga multi-domain structure, a display defect of an image can be preventedwhen the image is seen from a particular direction. Therefore, a viewingangle can be improved.

Note that the shape of the opening pattern is not limited to the shapeof this embodiment mode. Shapes of opening patterns described afterEmbodiment Mode 3 can also be applied. That is, the opening pattern alsoincludes a space in which a conductor pattern is not formed such as aspace between comb-shaped portions in a comb-shaped electrode, forexample.

Further, as shown in FIG. 1A, the first electrode 101 functioning as thecommon electrode protrudes outside the second electrode 112 functioningas the pixel electrode, when seen from a direction which isperpendicular to the substrate 100. Therefore, the problem is suppressedin which the second electrode 112 which is in a floating state after asignal is received is affected by a signal transmitted to another pixelthrough the source wiring 108. Accordingly, an image defect such ascrosstalk can be reduced. Note that the invention is not limited to suchan electrode structure, and a part of the common electrode may beprovided inside the pixel electrode.

A first alignment film 113 and liquid crystals 114 are stacked over thesecond interlayer insulating film 111 and the second electrode 112. Asthe liquid crystals 114, ferroelectric liquid crystals (FLC), nematicliquid crystals, smectic liquid crystals, liquid crystals withhomogeneous alignment, liquid crystals with homeotropic alignment, orthe like can be used. An opposite substrate 120 is provided over theliquid crystals 114 with a second alignment film 115 and a color filter116 interposed therebetween. Note that polarizing plates 119 and 118 areprovided for the substrate 100 and the opposite substrate 120.

Note also that a retardation plate, a λ/4 plate, or the like is oftenprovided in addition to such a polarizing plate.

Note that in the above-described structure, a capacitor is formed by aportion in which the opening pattern is not formed in the firstelectrode 101 and the second electrode 112, and each insulating filmlocated between the first electrode 101 and the second electrode 112.Since this capacitor is formed, storage capacitance is increased.

Next, an example of a method for manufacturing a semiconductor device ora liquid crystal display device of the invention is described. First, aconductive film having a light-transmitting property (e.g., an ITO(Indium Tin Oxide) film, an IZO film, a ZnO film, or a Si film) isformed over the substrate 100. Subsequently, a photoresist film (notshown) is formed over this conductive film, and this photoresist film isexposed and developed. Thus, a resist pattern is formed over theconductive film. Subsequently, the conductive film is etched by usingthis resist pattern as a mask. Thus, the conductive film is selectivelyremoved to form the first electrode 101 over the substrate 100. Afterthat, the resist pattern is removed.

Subsequently, the insulating film 102 is formed over the substrate 100and the first electrode 101. It is preferable that the insulating film102 be formed thicker than the gate insulating film 104 described later.Subsequently, a semiconductor film (e.g., a polysilicon film) is formedover the insulating film 102, and this semiconductor film is selectivelyremoved by etching using a resist pattern. Thus, the island-shapedsemiconductor film 103 is formed over the insulating film 102.

Subsequently, the gate insulating film 104 is formed over thesemiconductor film 103 and the insulating film 102. For example, thegate insulating film 104 is a silicon oxynitride film or a silicon oxidefilm, and is formed by plasma CVD. Note that the gate insulating film104 may be formed of a silicon nitride film or a multi-layer film ofsilicon nitride and silicon oxide. Subsequently, a conductive film isformed over the gate insulating film 104, and is selectively removed byetching using a resist pattern as the mask. Thus, the gate electrodes105 a and 105 b are formed over the gate insulating film 104 locatedover the semiconductor film 103. In addition, the gate wiring 105 andthe auxiliary wiring 106 are formed in this step.

Note that as described above, by providing the auxiliary wiring 106, thepotential of the first electrode 101 in each pixel can be stabilized. Inaddition, the auxiliary wiring 106 is not necessarily provided. Further,the auxiliary wiring 106 may be provided in another layer (e.g., a layerwhich is the same as the source wiring 108, a layer which is the same asthe first electrode 101, or a layer which is the same as the secondelectrode 112), or may be divided and formed in a plurality of layers.Although the auxiliary wiring 106 is extended in a direction which isperpendicular to the source wiring 108 in FIG. 1B, the auxiliary wiring106 may be extended in the same direction as the source wiring 108.

Note that the conductive film is formed to have one element or aplurality of elements selected from a group of aluminum (Al), tantalum(Ta), titanium (Ti), molybdenum (Mo), tungsten (W), neodymium (Nd),chromium (Cr), nickel (Ni), platinum (Pt), gold (Au), silver (Ag),copper (Cu), magnesium (Mg), scandium (Sc), cobalt (Co), zinc (Zn),niobium (Nb), silicon (Si), phosphorus (P), boron (B), arsenic (As),gallium (Ga), indium (In), tin (Sn), and oxygen (O), a compound or analloy material including one or a plurality of the elements selectedfrom the group as a component (e.g., Indium Tin Oxide (ITO), Indium ZincOxide (IZO), Indium Tin Oxide to which silicon oxide is added (ITSO),zinc oxide (ZnO), aluminum neodymium (Al—Nd), or magnesium silver(Mg—Ag)), a substance in which these compounds are combined, or thelike. Alternatively, the conductive film is formed to have a compound ofsilicon and the above-described material (silicide) (e.g., aluminumsilicon, molybdenum silicon, or nickel silicide) or a compound ofnitrogen and the above-described material (e.g., titanium nitride,tantalum nitride, or molybdenum nitride). Note also that a large amountof n-type impurities (e.g., phosphorus) or p-type impurities (e.g.,boron) may be included in silicon (Si).

Note that a wiring or an electrode may be formed of the above-describedmaterial with a single-layer structure or a multi-layer structure. Byforming the wiring or the electrode with a single-layer structure, amanufacturing process can be simplified;

the number of days for a process can be reduced; and cost can bereduced. Alternatively, by forming the wiring or the electrode with amulti-layer structure, an advantage of each material is taken and adisadvantage thereof is reduced so that a wiring or an electrode withhigh performance can be formed. For example, by including a materialwith low resistance (e.g., aluminum) in a multi-layer structure,resistance in the wiring can be reduced. In addition, by including amaterial with high heat resistance, for example, by employing astacked-layer structure in which a material with low heat resistance andhaving a different advantage is sandwiched with materials with high heatresistance, heat resistance in the wiring or the electrode as a wholecan be improved. For example, it is preferable that a stacked-layerstructure be employed in which a layer including aluminum is sandwichedwith layers including molybdenum or titanium. Further, when there is aportion which is in direct contact with a wiring, an electrode, or thelike formed of another material, they may be adversely affected eachother. For example, in some cases, one material enters the othermaterial and changes property thereof, so that an original purposecannot be achieved; and there occurs a problem in manufacturing so thatnormal manufacturing cannot be performed. In such a case, by sandwichingor covering a certain layer with different layers, the problem can besolved. For example, when Indium Tin Oxide (ITO) is to be in contactwith aluminum, it is preferable to interpose titanium or molybdenumtherebetween.

Moreover, when silicon is to be in contact with aluminum, it ispreferable to interpose titanium or molybdenum therebetween.

Subsequently, an impurity is added to the semiconductor film 103 byusing the gate electrodes 105 a and 105 b as masks. Thus, the impurityregions 103 a and 103 b and an impurity region located between the gateelectrodes 105 a and 105 b are formed in the semiconductor film 103.Note that an n-type impurity element and a p-type impurity element maybe separately added, or both of the n-type impurity element and thep-type impurity element may be added to a particular region. In thelatter case, the amount of addition of one of the n-type impurityelement and the p-type impurity element is to be larger than the otherthereof. In this step, a resist pattern may be used as the mask.

In addition, at this time, by changing the thickness or thestacked-layer structure of the gate insulating film 104, an LDD regionmay be formed. In a portion where the LDD region is to be formed, thegate insulating film 104 may be thickened or the number of layers may beincreased. Accordingly, since the amount of addition of impuritiesdecreases, the LDD region can be easily formed.

Note that impurity addition to the semiconductor film 103 may beperformed before the gate electrodes 105 a and 105 b are formed, forexample, before or after the gate insulating film 104 is formed. In thatcase, a resist pattern is used as the mask. Thus, a capacitor can beformed between an electrode of the same layer as a gate and thesemiconductor film to which the impurity is added. Since the gateinsulating film is provided between the electrode of the same layer asthe gate and the semiconductor film to which the impurity is added, athin and large capacitor can be formed.

Subsequently, the first interlayer insulating film 107 and each contacthole are formed. Subsequently, a conductive film (e.g., a metal film) isformed over the first interlayer insulating film 107 and in each contacthole, and this conductive film is selectively removed by etching using aresist pattern. Thus, the source wiring 108, the conductive film forconnecting 109, and the conductive film for connecting 110 are formed.

Subsequently, the second interlayer insulating film 111 and each contacthole are formed. Subsequently, a conductive film (e.g., an ITO film, anIZO film, a ZnO film, or a Si film) having a light-transmitting propertyis formed over the second interlayer insulating film 111 and in eachcontact hole, and this conductive film is selectively removed by etchingusing a resist pattern. Thus, the second electrode 112 is formed.

Positions are different between the contact hole in which a part of theconductive film for connecting 109 is embedded and the contact hole inwhich a part of the second electrode 112 is embedded. Thus, even whenportions located over the contact holes in the conductive film forconnecting 109 and the second electrode 112 hollow, these hollows do notoverlap with each other. Therefore, a portion which deeply hollows isnot formed in the second electrode 112, so that generation of a defectof the above-described resist pattern can be suppressed. After that, theresist pattern is removed.

Subsequently, the first alignment film 113 is formed, so that the liquidcrystals 114 are sealed between the first alignment film 113 and theopposite substrate 120 provided with the second alignment film 115 isformed. After that, the polarizing plates 118 and 119, a retardationplate (not shown), an optical film such as a λ/4 plate (not shown), anoptical film such as a diffusion plate or a prism sheet, or the like areprovided on sides which are not in contact with the liquid crystals 114of the opposite substrate 120 and the substrate 100. Further, abacklight or a frontlight is provided. As a backlight, an underneathtype or a sidelight type can be used. As a light source, a cold cathodetube or an LED (a light-emitting diode) can be used. As an LED, a whiteLED or a combination of LEDs of respective colors (e.g., white, red,blue, green, cyan, magenta, and/or yellow) may be used. By using an LED,a peak of a wavelength of light is sharp, so that color purity can beimproved. In the case of a sidelight type, a light guide plate isprovided and a uniform surface light source is realized. The liquidcrystal display device is formed in this manner.

Note that the liquid crystal display device may only mean a substrate,an opposite substrate, and liquid crystals sandwiched therebetween. Theliquid crystal display device may further include an optical film suchas a polarizing plate or retardation plate. Further, the liquid crystaldisplay device may also include a diffusion plate, a prism sheet, alight source (e.g., a cold cathode tube or an LED), or a light guideplate.

As described above, in accordance with Embodiment Mode 2 of theinvention, the first electrode 101 is provided over the substrate 100,that is, below the insulating film 102 in the liquid crystal displaydevice which controls the alignment direction of liquid crystals by theFFS-mode. Therefore, the interval between the first electrode 101 andthe second electrode 112 can be more increased compared with the casewhere the first electrode 101 is provided over the insulating film 102.Accordingly, degree of freedom of the interval between the firstelectrode 101 and the second electrode 112 is improved. Accordingly,since optimal values for an arrangement interval and width of theopening pattern of the pixel electrode change depending on a distancebetween the pixel electrode and the common electrode, the size, thewidth, and the interval of the opening pattern can be freely set. Then,a gradient of an electric field applied between the electrodes can becontrolled, so that, for example, an electric field parallel to thesubstrate can be easily increased. That is, since liquid crystalmolecules which are aligned in parallel to the substrate (so-calledhomogeneous alignment) can be controlled in a direction parallel to thesubstrate in a display device using liquid crystals, a viewing angle iswidened by applying an optimal electric field.

In addition, an operation or the like of the transistor is not affectedeven when thickness of the insulating film 102 is changed, so that thethickness thereof can be freely controlled. Therefore, the intervalbetween the first electrode 101 and the second electrode 112 can befreely increased.

By thickening the insulating film 102, the interval between the firstelectrode 101 and the second electrode 112 is increased even when thegate insulating film 104 is thinned, so that an appropriate electricfield can be applied to the liquid crystals 114. When the gateinsulating film 104 is thinned, current drive capability of the thinfilm transistor 121 can be improved and gate capacitance thereof can beimproved.

In addition, the gate electrode 105 a and the gate wiring 105 may beformed in different layers, or may be formed of different materials.

Although the conductive film for connecting 109 is provided in the samelayer as the source wiring 108, the conductive film for connecting 109may be provided in another wiring layer (e.g., the same layer as thegate wiring 105, the first electrode 101, or the second electrode 112).In addition, the gate insulating film 104 is not necessarily formed overthe whole surface.

The contact hole in which a part of the second electrode 112 is embeddedmay be formed in a position which overlaps with the contact hole inwhich a part of the conductive film for connecting 109 is embedded. Inthis case, since the contact holes can be put in one position, layoutcan be efficiently performed. Therefore, an aperture ratio of the pixelcan be improved.

In this embodiment mode, the thin film transistor in which the gateelectrode is provided over the channel region, namely, a so-calledtop-gate thin film transistor is described; however, the invention isnot particularly limited to this. A thin film transistor in which a gateelectrode is provided below a channel region, namely, a so-calledbottom-gate thin film transistor may be formed, or a transistor having astructure in which gate electrodes are provided over and below a channelregion may be formed.

In addition, the liquid crystal display device may be a transmissiveliquid crystal display device, a semi-transmissive liquid crystaldisplay device, or a reflective liquid crystal display device. Thesemi-transmissive liquid crystal display device can be achieved byforming the first electrode 101 with a film having a light-transmittingproperty (e.g., an ITO (Indium Tin Oxide) film, an IZO (Indium ZincOxide) film, a ZnO film, or a polysilicon film or an amorphous siliconfilm into which an impurity is introduced) and forming the secondelectrode 112 with a metal film. Alternatively, the semi-transmissiveliquid crystal display device can be achieved by forming the secondelectrode 112 with a film having a light-transmitting property, forminga part of the first electrode 101 with a metal film, and forming theother part thereof with a film having a light-transmitting property.Further, in the reflective liquid crystal display device, the firstelectrode 101 can have a function of a reflector by forming the firstelectrode 101 with a metal film. By providing an insulating film (e.g.,a silicon oxide film) between the substrate 100 and the first electrode101, a metal film as a reflective film can be formed in this insulatingfilm. Moreover, a reflective sheet as a reflective film (e.g., analuminum film) can also be formed on a surface outside of the substrate100. Note that the contents described here can be similarly applied toeach embodiment mode described later.

Embodiment Mode 3

FIG. 3A is a plan view showing a structure of a liquid crystal displaydevice in accordance with Embodiment Mode 3. FIG. 3B is across-sectional view taken along a line E-F and a line G-H in FIG. 3A.This embodiment mode describes a structure which is almost similar tothat of Embodiment Mode 2 except for the following points. The firstelectrode 101 is electrically connected to the impurity region 103 b ofthe thin film transistor 121 and functions as a pixel electrode; thesecond electrode 112 is electrically connected to the auxiliary wiring106 and functions as a common electrode; the second electrode 112protrudes outside of the first electrode 101 when seen from a directionwhich is perpendicular to the substrate 100; and connection structuresof the first electrode 101 and the second electrode 112 to each wiringare different. In addition, a manufacturing method of the liquid crystaldisplay device in accordance with this embodiment mode is almost similarto that of Embodiment Mode 2. Accordingly, the contents described inEmbodiment Mode 2 can also be applied to this embodiment mode.Hereinafter, common reference numerals are used for portions havingsimilar structures to Embodiment Mode 2 and description thereof isomitted.

In this embodiment, a contact hole located over the first electrode 101is formed in the first interlayer insulating film 107, the gateinsulating film 104, and the insulating film 102. Contact holes locatedover the impurity regions 103 a and 103 b of the thin film transistor121 are formed in the first interlayer insulating film 107 and the gateinsulating film 104. In addition, a contact hole located over theauxiliary wiring 106 is formed in the first interlayer insulating film107.

The conductive film for connecting 109 is extended above from theimpurity region 103 b to the first electrode 101, and is electricallyconnected to each of the impurity region 103 b and the first electrode101 by being partially embedded in the contact hole. In this manner, thefirst electrode 101 is electrically connected to the impurity region 103b with the conductive film for connecting 109 interposed therebetween.In addition, the conductive film for connecting 110 is electricallyconnected to the auxiliary wiring 106 by being partially embedded in thecontact hole.

The first electrode 101 may be provided with a conductive film forconnecting formed in the same layer as the second electrode 112 and maybe electrically connected to the impurity region 103 b with theconductive film for connecting interposed therebetween.

In addition, a contact hole located over the conductive film forconnecting 110 is formed in the second interlayer insulating film 111.The second electrode 112 is electrically connected to the conductivefilm for connecting 110 by being partially embedded in the contact hole.In this manner, the second electrode 112 is electrically connected tothe auxiliary wiring 106 with the conductive film for connecting 110interposed therebetween. Note that as shown in FIG. 3A, the secondelectrodes 112 located above and below are partially connected to eachother.

Note that the auxiliary wiring 106 and the second electrode 112 may alsobe directly connected without providing the conductive film forconnecting 110.

In this embodiment mode, the conductive film for connecting 110 isformed above each of three corners except for a corner near the thinfilm transistor among four corners of the first electrode 101.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. Note thatin this embodiment mode, the conductive film for connecting 110 is notnecessarily provided. In this case, a contact hole located over theauxiliary wiring 106 is formed in the first and second interlayerinsulating films 107 and 111. Then, the second electrode 112 ispartially embedded in this contact hole, so that the auxiliary wiring106 and the second electrode 112 are electrically connected. In thiscase, an aperture ratio can be improved. Note also that by providing theconductive film for connecting 110, location deviation can be suppressedby the conductive film for connecting 110 even when location deviationis generated in the contact holes formed in the first and secondinterlayer insulating films 107 and 111.

In addition, as shown in FIG. 3B, the first electrode 101 functions asthe pixel electrode and the second electrode 112 functions as the commonelectrode, and the common electrode is provided to be closer to theliquid crystals than the pixel electrode. Accordingly, since a voltageof the common electrode is constant even when a voltage of the pixelelectrode fluctuates for each pixel, an electric field of a portion inwhich the liquid crystals are provided is hardly affected by an adjacentpixel, so that crosstalk can be reduced. For example, although signalsinput into pixels adjacent to each other may be greatly different fromeach other depending on an image to be displayed, crosstalk can beprevented by employing a structure where a common electrode are providedso as to be close to liquid crystals like this embodiment mode.

Note that although only one pixel is shown in FIG. 3A, a plurality ofpixels are actually arranged in matrix. In this case, the secondelectrodes 112 of the pixels may be connected to each other. Thus,resistance is lowered and a voltage can be sufficiently applied to thesecond electrode 112.

Note that this embodiment mode shows an example of the case where thecontents described in Embodiment Mode 2 are partly changed, improved, ortransformed. Accordingly, the contents described in Embodiment Mode 2can also be applied to this embodiment mode or can be combined with thisembodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

Embodiment Mode 4

FIG. 4A is a plan view showing a structure of a liquid crystal displaydevice in accordance with Embodiment Mode 4. FIG. 4B is across-sectional view taken along a line A-B and a line C-D in FIG. 4A ofthe invention. The liquid crystal display device in accordance with thisembodiment mode has a structure which is almost similar to that ofEmbodiment Mode 3 except for the following points. A shape of theopening pattern 112 c formed in the second electrode 112 is different;and an opening pattern 101 a is formed in the first electrode 101. Thatis, the liquid crystal display device in accordance with this embodimentmode is a device which controls an alignment direction of liquidcrystals by an IPS mode, and a pixel electrode and a common electrodeare alternate and almost parallel to each other when seen from adirection which is perpendicular to the liquid crystal display device.In an FFS mode, the electrode located below which is the pixel electrodeor the common electrode has an opening pattern. In addition, amanufacturing method of the liquid crystal display device in accordancewith this embodiment mode is almost similar to that of Embodiment Mode3. Accordingly, the contents described in Embodiment Mode 3 can also beapplied to this embodiment mode. Note that since the contents describedin Embodiment Mode 2 can also be applied to Embodiment Mode 3, thecontents described in Embodiment Mode 2 can also be applied toEmbodiment Mode 4. Hereinafter, common reference numerals are used forportions having similar structures to Embodiment Mode 3 and descriptionthereof is omitted.

Each of the opening patterns 112 c and 101 a is extended longitudinallyin a zigzag manner in FIG. 4A. The opening pattern 101 a is locatedbelow and around a region where the opening pattern 112 c is not formedin the second electrode 112.

By providing opening patterns having different directions like theopening patterns 112 c and 101 a, a plurality of regions havingdifferent moving directions of liquid crystal molecules can also beprovided. That is, a multi-domain structure can be formed. By employinga multi-domain structure, a display defect of an image when the image isseen from a particular direction can be prevented. Therefore, a viewingangle can be improved.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 3 can be obtained. In thisembodiment mode, shapes of the second electrode 112 and the openingpattern 112 c, and shapes of the first electrode 101 and the openingpattern 101 a may be the shapes of the second electrode 112 and theopening pattern 112 c in Embodiment Mode 2. Note that it is necessary toprovide the opening patterns 101 a and 112 c so as to be alternate andalmost parallel to each other except for peripheral portions of thefirst electrode 101 and the second electrode 112 when seen from adirection which is perpendicular to the substrate 100. Note also thatthe invention is not limited to this.

In addition, in the FFS-mode liquid crystal display device shown inEmbodiment Mode 2 or 3, the shapes of the second electrode 112 and theopening patterns 112 a and 112 b may be the shapes shown in thisembodiment mode.

Further, a capacitor can be formed by making the first electrode 101overlap with the second electrode 112 or the auxiliary wiring 106, andthe capacitor can be used as a storage capacitor.

Note that this embodiment mode shows an example of the case where thecontents described in Embodiment Modes 2 and 3 are partly changed,improved, or transformed. Accordingly, the contents described inEmbodiment Modes 2 and 3 can also be applied to this embodiment mode orcan be combined with this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

Embodiment Mode 5

FIG. 5A is a plan view showing a structure of an IPS-mode liquid crystaldisplay device in accordance with Embodiment Mode 5 of the invention.FIG. SB is a cross-sectional view taken along a line A-B and a line C-Din FIG. 5A. This embodiment mode describes a structure which is almostsimilar to that of Embodiment Mode 4 except for the following points.The first electrode 101 is electrically connected to the auxiliarywiring 106 and functions as a common electrode; the second electrode 112is electrically connected to the conductive film for connecting 109 andfunctions as a pixel electrode; and connection structures of the firstelectrode 101 and the second electrode 112 to each wiring are different.In addition, a manufacturing method of the liquid crystal display devicein accordance with this embodiment mode is almost similar to that ofEmbodiment Mode 4. Hereinafter, common reference numerals are used forportions having similar structures to Embodiment Mode 4 and descriptionthereof is omitted.

Accordingly, the contents described in Embodiment Modes 1 to 4 can alsobe applied to this embodiment mode.

In this embodiment, the conductive film for connecting 110 shown inEmbodiment Mode 3 is not formed. Instead, a contact hole located overthe first electrode 101 is formed in the gate insulating film 104 andthe insulating film 102. The auxiliary wiring 106 is electricallyconnected to the first electrode 101 by being partially embedded in thiscontact hole.

Note that this contact hole is formed before the gate electrodes 105 aand 105 b are formed.

By providing this contact hole in this manner, layout can be efficientlyperformed and an aperture ratio can be improved.

Further, a contact hole located over the conductive film for connecting110 is not formed in the second interlayer insulating film 111, and acontact hole located over the conductive film for connecting 109 isformed instead of this. The second electrode 112 is electricallyconnected to the conductive film for connecting 109 by being partiallyembedded in this contact hole.

Although the second electrode 112 is electrically connected to theconductive film for connecting 109, the invention is not limited tothis. The second electrode 112 may also be electrically connected to theimpurity region 103 b without providing the conductive film forconnecting 109.

In this embodiment mode, shapes of the second electrode 112 and theopening pattern 112 c, and shapes of the first electrode 101 and theopening pattern 101 a may be the shapes of the second electrode 112 andthe opening pattern 112 c in Embodiment Mode 2. Note that it isnecessary to provide the opening patterns 101 a and 112 c so as to bealternate and almost parallel to each other except for peripheralportions of the first electrode 101 and the second electrode 112 whenseen from a direction which is perpendicular to the substrate 100.

By providing opening patterns having different directions like theopening patterns 112 c and 101 a, a plurality of regions havingdifferent moving directions of liquid crystal molecules can also beprovided. That is, a multi-domain structure can be formed. By employinga multi-domain structure, a display defect of an image when the image isseen from a particular direction can be prevented. Therefore, a viewingangle can be improved.

Note that this embodiment mode shows an example of the case where thecontents described in Embodiment Modes 2 to 4 are partly changed,improved, or transformed. Accordingly, the contents described inEmbodiment Modes 2 to 4 can also be applied to this embodiment mode orcan be combined with this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

Embodiment Mode 6

FIG. 6A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 6 of the invention.FIG. 6B is a cross-sectional view taken along a line E-F and a line G-Hin FIG. 6A. This embodiment mode describes a structure which is almostsimilar to that of the FFS-mode liquid crystal display device shown inEmbodiment Mode 2 except for the following points. The source wiring 108is inflected; the first electrode 101 and the second electrode 112 arealso inflected in accordance with the source wiring 108; and an openingpattern 112 h of the second electrode 112 is extended along the sourcewiring 108 and is inflected. Therefore, the contents described inEmbodiment Mode 2 can also be applied to this embodiment mode.Hereinafter, common reference numerals are used for portions havingsimilar structures to Embodiment Mode 2 and description thereof isomitted.

Accordingly, the contents described in Embodiment Modes 2 to 5 can alsobe applied to this embodiment mode.

By providing opening patterns having different directions like theopening patterns 112 h in FIG. 6A, a plurality of regions havingdifferent moving directions of liquid crystal molecules can also beprovided. That is, a multi-domain structure can be formed. By employinga multi-domain structure, a display defect of an image when the image isseen from a particular direction can be prevented. Therefore, a viewingangle can be improved.

Further, since the source wiring 108 is also inflected along the openingpattern 112 h, layout can be efficiently performed and an aperture ratiocan be improved.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. In thisembodiment mode, a shape of the opening pattern of the second electrode112 may be the shape shown in Embodiment Mode 2 or 4.

Note that this embodiment mode shows an example of the case where thecontents described in Embodiment Modes 2 to 5 are partly changed,improved, or transformed. Accordingly, the contents described inEmbodiment Modes 2 to 5 can also be applied to this embodiment mode orcan be combined with this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

Embodiment Mode 7

FIG. 7A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 7 of the invention.FIG. 7B is a cross-sectional view taken along a line E-F and a line G-Hin FIG. 7A. This embodiment mode describes a structure which is almostsimilar to that of the FFS-mode liquid crystal display device shown inEmbodiment Mode 3 except for the following points. The source wiring 108is inflected; the first electrode 101 and the second electrode 112 arealso inflected in accordance with the source wiring 108; and the openingpattern 112 h of the second electrode 112 is extended along the sourcewiring 108 and is inflected. Therefore, the contents described inEmbodiment Mode 3 can also be applied to this embodiment mode.Hereinafter, common reference numerals are used for portions havingsimilar structures to Embodiment Mode 3 and description thereof isomitted.

Accordingly, the contents described in Embodiment Modes 2 to 6 can alsobe applied to this embodiment mode.

By providing opening patterns having different directions like theopening patterns 112 h in FIG. 7A, a plurality of regions havingdifferent moving directions of liquid crystal molecules can also beprovided. That is, a multi-domain structure can be formed. By employinga multi-domain structure, a display defect of an image when the image isseen from a particular direction can be prevented. Therefore, a viewingangle can be improved.

Further, since the source wiring 108 is also inflected along the openingpattern 112 h, layout can be efficiently performed and an aperture ratiocan be improved.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 3 can be obtained. In thisembodiment mode, a shape of the opening pattern of the second electrode112 may be the shape shown in Embodiment Mode 2 or 4.

Note that this embodiment mode shows an example of the case where thecontents described in Embodiment Modes 2 to 6 are partly changed,improved, or transformed. Accordingly, the contents described inEmbodiment Modes 2 to 6 can also be applied to this embodiment mode orcan be combined with this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

Embodiment Mode 8

FIG. 8A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 8 of the invention.FIG. 8B is a cross-sectional view taken along a line E-F and a line G-Hin FIG. 8A. This embodiment mode describes a structure which is almostsimilar to that of Embodiment Mode 2 except that a conductive film 160located below the whole surface of the semiconductor film 103 is formedover the substrate 100. In addition, a manufacturing method of theliquid crystal display device in accordance with this embodiment mode isalmost similar to that of Embodiment Mode 2 except that the conductivefilm 160 is formed in the same step as the first electrode 101.Therefore, the contents described in Embodiment Mode 2 can also beapplied to this embodiment mode. Note that the conductive film 160 isnot electrically connected to any component and is in a floating state.Hereinafter, common reference numerals are used for portions havingsimilar structures to Embodiment Mode 2 and description thereof isomitted.

Accordingly, the contents described in Embodiment Modes 2 to 7 can alsobe applied to this embodiment mode.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. Inaddition, since the conductive film 160 located below the semiconductorfilm 103 is formed over the substrate 100, the insulating film 102 maybe a single layer of a silicon oxide film. When the conductive film 160is not formed and the insulating film 102 is a single layer of a siliconoxide film, there is a possibility that impurity diffusion from thesubstrate 100 to the semiconductor film 103 cannot be sufficientlysuppressed. Therefore, it is necessary to add a silicon nitride film tothe insulating film 102. However, an operation of the thin filmtransistor 121 becomes unstable when the silicon nitride film is made incontact with the semiconductor film 103. However, in this embodimentmode, by forming the conductive film 160, impurity diffusion from thesubstrate 100 to the semiconductor film 103 can be sufficientlysuppressed even when the insulating film 102 is a single layer of asilicon oxide film. Further, by forming the insulating film 102 of thesingle layer of silicon oxide film, the operation of the thin filmtransistor 121 can be stabilized.

Note that the insulating film 102 may be a stacked-layer structure of asilicon oxide film and a silicon nitride film. Thus, even when animpurity such as iron is included in the silicon oxide film, diffusionof this impurity to the semiconductor film 103 can be suppressed. Inaddition, impurity penetration from the substrate 100 can be blockedmore efficiently.

Note that by forming the conductive film 160 in each of the FFS-modeliquid crystal display device shown in Embodiment Mode 3, and theIPS-mode liquid crystal display devices shown in Embodiment Mode 4 and5, an advantageous effect which is similar to that of this embodimentmode can be obtained. In addition, in this embodiment mode, shapes ofthe second electrode 112 and the opening pattern 112 a may be the shapesshown in Embodiment Mode 4.

By providing opening patterns having different directions like theopening patterns 112 a and 112 b, a plurality of regions havingdifferent moving directions of liquid crystal molecules can also beprovided. That is, a multi-domain structure can be formed. By employinga multi-domain structure, a display defect of an image when the image isseen from a particular direction can be prevented. Therefore, a viewingangle can be improved.

Note that this embodiment mode shows an example of the case where thecontents described in Embodiment Modes 2 to 7 are partly changed,improved, or transformed. Accordingly, the contents described inEmbodiment Modes 2 to 7 can also be applied to this embodiment mode orcan be combined with this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

Embodiment Mode 9

FIG. 9A is a plan view showing a structure of an FFS-mode liquid crystaldisplay device in accordance with Embodiment Mode 9 of the invention.FIG. 9B is a cross-sectional view taken along a line E-F and a line G-Hin FIG. 9A. This embodiment mode describes a structure which is almostsimilar to that of Embodiment Mode 2 except that a part of the firstelectrode 101 is extended to below the impurity region 103 b in thesemiconductor film 103. In addition, a manufacturing method of theliquid crystal display device in accordance with this embodiment mode isalmost similar to that of Embodiment Mode 2. Therefore, the contentsdescribed in Embodiment Mode 2 can also be applied to this embodimentmode. Hereinafter, common reference numerals are used for portionshaving similar structures to Embodiment Mode 2 and description thereofis omitted.

Accordingly, the contents described in Embodiment Modes 2 to 8 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. In thisembodiment mode, shapes of the second electrode 112 and the openingpattern 112 a may be the shapes shown in Embodiment Mode 4. In addition,in each of the FFS-mode liquid crystal display device shown inEmbodiment Mode 6 and the IPS-mode liquid crystal display device shownin Embodiment Mode 5, a part of the first electrode 101 may be locatedbelow the impurity region 103 b, similarly to this embodiment mode.

In addition, in each of the FFS-mode liquid crystal display devicesshown in Embodiment Modes 3 and 7, and the IPS-mode liquid crystaldisplay device shown in Embodiment Mode 4, a part of the first electrode101 may be located below the impurity region 103 b, similarly to thisembodiment mode. Thus, since a voltage of the first electrode 101 is thesame as a voltage of the impurity region 103 b, the liquid crystaldisplay device is hardly affected by noise or the like so that thevoltage of the impurity region 103 b is stabilized. Accordingly, sincean interval between the opening patterns 112 a can be reduced and anelectric field is applied smoothly, liquid crystal molecules can beeasily controlled. Further, since the voltage can be lowered by reducingthe interval between the opening patterns 112 a, power consumption canbe reduced. Moreover, since electric field crowding can be relieved,reliability of the thin film transistor 121 can also be improved.

In addition, in this embodiment mode, a portion located below theimpurity region 103 b in the first electrode 101 may be separated from amain body of the first electrode 101 and be electrically connected tothe conductive film for connecting 109. Thus, the advantageous effectcan also be obtained. That is, the liquid crystal molecules are easilycontrolled, power consumption is reduced, and reliability of the thinfilm transistor 121 is improved.

Embodiment Mode 10

FIG. 10A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 10 of theinvention. FIG. 10B is a cross-sectional view taken along a line E-F anda line G-FI in FIG. 10A. This embodiment mode describes a structurewhich is almost similar to that of Embodiment Mode 9 except that a partof the first electrode 101 is extended to below each of the impurityregion 103 b, two channel regions 103 c, and an impurity region betweenthe channel regions 103 c in the semiconductor film 103. In addition, amanufacturing method of the liquid crystal display device in accordancewith this embodiment mode is almost similar to that of Embodiment Mode9. Therefore, the contents described in Embodiment Mode 9 can also beapplied to this embodiment mode. Hereinafter, common reference numeralsare used for portions having similar structures to Embodiment Mode 9 anddescription thereof is omitted.

Accordingly, the contents described in Embodiment Modes 2 to 9 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 9 can be obtained. Inaddition, in each of the FFS-mode liquid crystal display device shown inEmbodiment Mode 6 and the IPS-mode liquid crystal display device shownin Embodiment Mode 5, a part of the first electrode 101 may also beextended to below each of the impurity region 103 b, the two channelregions 103 c, and the impurity region between the channel regions 103c, similarly to this embodiment mode.

Note that in this embodiment mode, shapes of the second electrode 112and the opening pattern 112 a may be the shapes shown in Embodiment Mode4.

In addition, in each of the FFS-mode liquid crystal display devicesshown in Embodiment Mode 3 and 7, and the IPS-mode liquid crystaldisplay device shown in Embodiment Mode 4, a part of the first electrode101 may also be extended to below each of the impurity region 103 b, thetwo channel regions 103 c, and the impurity region between the channelregions 103 c, similarly to this embodiment mode. Thus, since a voltageof the first electrode 101 is the same as a voltage of the impurityregion 103 b, the liquid crystal display device is hardly affected bynoise or the like so that the voltage of the impurity region 103 b isstabilized. Accordingly, since an interval between the opening patterns112 a can be reduced and an electric field is applied smoothly, liquidcrystal molecules can be easily controlled. Further, since the voltagecan be lowered by reducing the interval between the opening patterns 112a, power consumption can be reduced. Moreover, since electric fieldcrowding can be relieved, reliability of the thin film transistor 121can also be improved.

In addition, in this embodiment mode, a portion located below each ofthe impurity region 103 b, the two channel regions 103 c, and theimpurity region between the channel regions 103 c in the first electrode101 may be separated from the main body of the first electrode 101 andbe electrically connected to the conductive film for connecting 109.Thus, the advantageous effect can also be obtained. That is, the liquidcrystal molecules are easily controlled, power consumption is reduced,and reliability of the thin film transistor 121 is improved.

Embodiment Mode 11

FIG. 11A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 11 of theinvention. FIG. 11B is a cross-sectional view taken along a line E-F anda line G-H in FIG. 11A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 10 except that a part ofthe first electrode 101 is extended to below the whole surface of thesemiconductor film 103. In addition, a manufacturing method of theliquid crystal display device in accordance with this embodiment mode isalmost similar to that of Embodiment Mode 10. Therefore, the contentsdescribed in Embodiment Mode 10 can also be applied to this embodimentmode. Hereinafter, common reference numerals are used for portionshaving similar structures to Embodiment Mode 10 and description thereofis omitted.

Accordingly, the contents described in Embodiment Modes 2 to 10 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 10 can be obtained. Inaddition, by an action which is similar to that of Embodiment Mode 8,even when the insulating film 102 is formed of a single-layer of asilicon oxide film, impurity diffusion from the substrate 100 to thesemiconductor film 103 can be sufficiently suppressed. In addition, byforming the insulating film 102 of the single layer of the silicon oxidefilm, the operation of the thin film transistor 121 can be stabilized.

Note that in this embodiment mode, shapes of the second electrode 112and the opening pattern 112 a may be the shapes shown in Embodiment Mode4. In addition, in each of the FFS-mode liquid crystal display deviceshown in Embodiment Mode 6 and the IPS-mode liquid crystal displaydevice shown in Embodiment Mode 5, a part of the first electrode 101 mayalso be extended to below the whole of the semiconductor film 103,similarly to this embodiment mode.

In addition, in each of the FFS-mode liquid crystal display devicesshown in Embodiment Mode 3 and 7, and the IPS-mode liquid crystaldisplay device shown in Embodiment Mode 4, a part of the first electrode101 may also be extended to below each of the impurity region 103 b, thetwo channel regions 103 c, and the impurity region between the channelregions 103 c, similarly to this embodiment mode. Thus, since a voltageof the first electrode 101 is the same as a voltage of the impurityregion 103 b, the liquid crystal display device is hardly affected bynoise or the like so that the voltage of the impurity region 103 b isstabilized. Accordingly, since an interval between the opening patterns112 a can be reduced and an electric field is applied smoothly, liquidcrystal molecules can be easily controlled. Further, since the voltagecan be lowered by reducing the interval between the opening patterns 112a, power consumption can be reduced. Moreover, since electric fieldcrowding can be relieved, reliability of the thin film transistor 121can also be improved.

In addition, in this embodiment mode, a portion located below thesemiconductor film 103 in the first electrode 101 may be separated fromthe main body of the first electrode 101 and be electrically connectedto the conductive film for connecting 109. Thus, the advantageous effectcan also be obtained. That is, the liquid crystal molecules are easilycontrolled, power consumption is reduced, and reliability of the thinfilm transistor 121 is improved.

Embodiment Mode 12

FIG. 12A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 12 of theinvention. FIG. 12B is a cross-sectional view taken along a line E-F anda line G-H in FIG. 12A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 2 except for the followingpoints. A conductive film 170 located below the impurity region 103 awhich is electrically connected to the source wiring 108 insemiconductor film 103 is formed over the substrate 100; and theconductive film 170 is electrically connected to the source wiring 108.In addition, a manufacturing method of the liquid crystal display devicein accordance with this embodiment mode is almost similar to that ofEmbodiment Mode 2 except that the conductive film 170 is formed in thesame step as the first electrode 101. Therefore, the contents describedin Embodiment Mode 2 can also be applied to this embodiment mode.Hereinafter, common reference numerals are used for portions havingsimilar structures to Embodiment Mode 2 and description thereof isomitted.

Accordingly, the contents described in Embodiment Modes 2 to 11 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

A contact hole located over the conductive film 170 is formed in thefirst interlayer insulating film 107, the gate insulating film 104, andthe insulating film 102. The source wiring 108 is electrically connectedto the conductive film 170 by being partially embedded in this contacthole.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. The samevoltage as that of the impurity region 103 a is also applied to theconductive film 170 located below the impurity region 103 a which iselectrically connected to the source wiring 108. Accordingly, thevoltage of the impurity region 103 a is stabilized.

Note that in each of the FFS-mode liquid crystal display devices shownin Embodiment Modes 3, 6, 7, 9, and 10, and the IPS-mode liquid crystaldisplay devices shown in Embodiment Modes 4 and 5, the conductive film170 which is similar to that of this embodiment mode may also be formed.Thus, an advantageous effect which is similar to that of this embodimentmode can be obtained, for example, the voltage of the impurity region103 a can be stabilized. In addition, in this embodiment mode, shapes ofthe second electrode 112 and the opening pattern 112 a may be the shapesshown in Embodiment Mode 4.

Embodiment Mode 13

FIG. 13A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 13 of theinvention. FIG. 13B is a cross-sectional view taken along a line E-F anda line G-H in FIG. 13A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 12 except for the followingpoints. The conductive film 170 is formed below the channel region 103 cwhich is adjacent to the impurity region 103 a and the impurity region103 a in the semiconductor film 103; and a part of the first electrode101 is formed below the channel region 103 c which is adjacent to theimpurity region 103 b and the impurity region 103 b in the semiconductorfilm 103. In addition, a manufacturing method of the liquid crystaldisplay device in accordance with this embodiment mode is almost similarto that of Embodiment Mode 12. Therefore, the contents described inEmbodiment Mode 12 can also be applied to this embodiment mode.Hereinafter, common reference numerals are used for portions havingsimilar structures to Embodiment Mode 12 and description thereof isomitted.

Accordingly, the contents described in Embodiment Modes 2 to 12 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing. In accordance withthis embodiment mode also, advantageous effects which are similar tothose of Embodiment Modes 9 and 12 can be obtained. Note that in each ofthe FFS-mode liquid crystal display devices shown in Embodiment Mode 3,6, and 7, and the IPS-mode liquid crystal display devices shown inEmbodiment Mode 4 and 5, the conductive film 170 which is similar tothat of this embodiment mode may also be formed and a shape of the firstelectrode 101 may also be similar to that of this embodiment mode. Thus,an advantageous effect which is similar to that of this embodiment modecan be obtained. In addition, in this embodiment mode, shapes of thesecond electrode 112 and the opening pattern 112 a may be the shapesshown in Embodiment Mode 4.

Embodiment Mode 14

FIG. 14A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 14 of theinvention. FIG. 14B is a cross-sectional view taken along a line E-F anda line G-H in FIG. 14A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 12 except that theconductive film 170 is formed below each of the impurity region 103 a,two channel regions 103 c, and the impurity region between the channelregions 103 c in the semiconductor film 103. In addition, amanufacturing method of the liquid crystal display device in accordancewith this embodiment mode is almost similar to that of Embodiment Mode12. Therefore, the contents described in Embodiment Mode 12 can also beapplied to this embodiment mode. Hereinafter, common reference numeralsare used for portions having similar structures to Embodiment Mode 12and description thereof is omitted.

Accordingly, the contents described in Embodiment Modes 2 to 13 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

An advantageous effect which is similar to that of Embodiment Mode 12can be obtained In accordance with this embodiment mode also, forexample, the voltage of the impurity region 103 a can be stabilized.Note that in each of the FFS-mode liquid crystal display devices shownin Embodiment Modes 3, 6, 7, and 9, and the IPS-mode liquid crystaldisplay devices shown in Embodiment Modes 4 and 5, the conductive film170 which is similar to that of this embodiment mode may also be formed.Thus, an advantageous effect which is similar to that of this embodimentmode can be obtained, for example, the voltage of the impurity region103 a can be stabilized. In addition, in this embodiment mode, shapes ofthe second electrode 112 and the opening pattern 112 a may be the shapesshown in Embodiment Mode 4.

Embodiment Mode 15

FIG. 15A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 15 of theinvention. FIG. 15B is a cross-sectional view taken along a line E-F anda line G-H in FIG. 15A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 14 except that theconductive film 170 is formed below the whole surface of thesemiconductor film 103. In addition, a manufacturing method of theliquid crystal display device in accordance with this embodiment mode isalmost similar to that of Embodiment Mode 14. Hereinafter, commonreference numerals are used for portions having similar structures toEmbodiment Mode 14 and description thereof is omitted.

Accordingly, the contents described in Embodiment Modes 2 to 14 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

An advantageous effect which is similar to that of Embodiment Mode 14can be obtained In accordance with this embodiment mode also, forexample, the voltage of the impurity region 103 a can be stabilized.Note that in each of the FFS-mode liquid crystal display devices shownin Embodiment Modes 3, 6, and 7, and the IPS-mode liquid crystal displaydevices shown in Embodiment Modes 4 and 5, the conductive film 170 whichis similar to that of this embodiment mode may also be formed. Thus, anadvantageous effect which is similar to that of this embodiment mode canbe obtained, for example, the voltage of the impurity region 103 a canbe stabilized. In addition, in this embodiment mode, shapes of thesecond electrode 112 and the opening pattern 112 a may be the shapesshown in Embodiment Mode 4.

Embodiment Mode 16

FIG. 16A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 16 of theinvention. FIG. 16B is a cross-sectional view taken along a line E-F anda line G-H in FIG. 16A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 2 except that a second gatewiring 180, and second gate electrodes 180 a and 180 b are formed overthe substrate 100. When seen from a direction which is almostperpendicular to the substrate 100, the second gate wiring 180, and thesecond gate electrodes 180 a and 180 b almost overlap with the gatewiring 105, and the gate electrodes 105 a and 105 b, respectively.

In addition, a manufacturing method of the liquid crystal display devicein accordance with this embodiment mode is almost similar to that ofEmbodiment Mode 2 except that the second gate wiring 180, and the secondgate electrodes 180 a and 180 b are formed in the same step as the firstelectrode 101. Accordingly, the contents described in Embodiment Mode 2can also be applied to this embodiment mode. Hereinafter, commonreference numerals are used for portions having similar structures toEmbodiment Mode 2 and description thereof is omitted.

Accordingly, the contents described in Embodiment Modes 2 to 15 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. Inaddition, two channel regions 103 c of the semiconductor film 103 aresandwiched between the gate electrode 105 a and the second gateelectrode 180 a or between the gate electrode 105 b and the second gateelectrode 180 b. Accordingly, since each channel region is substantiallydoubled, the amount of current flowing through the thin film transistor121 is increased.

Note that in each of the FFS-mode liquid crystal display devices shownin Embodiment Modes 3, 6, 7, 9, and 12, and the IPS-mode liquid crystaldisplay devices shown in Embodiment Modes 4 and 5, the second gatewiring 180, and the second gate electrodes 180 a and 180 b may also beformed in the same step as the first electrode 101, similarly to thisembodiment mode. Thus, an advantageous effect which is similar to thatof this embodiment mode can be obtained. In addition, in this embodimentmode, shapes of the second electrode 112 and the opening pattern 112 amay be the shapes shown in Embodiment Mode 4.

Embodiment Mode 17

FIG. 17A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 17 of theinvention. FIG. 17B is a cross-sectional view taken along a line E-F, aline G-H, and a line I-J in FIG. 17A. This embodiment mode describes astructure which is almost similar to that of Embodiment Mode 16 exceptthat the gate wiring 105 is not formed and the gate electrodes 105 a and105 b are electrically connected to the second gate wiring 180 through awiring for connecting 105 c. Accordingly, the contents described inEmbodiment Mode 16 can also be applied to this embodiment mode. Thewiring for connecting 105 c is formed in the same wiring layer as thegate electrodes 105 a and 105 b.

Accordingly, the contents described in Embodiment Modes 2 to 16 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

A contact hole located over the second gate wiring 180 is formed in theinsulating film 102 and the gate insulating film 104. The wiring forconnecting 105 c is electrically connected to the second gate wiring 180by being partially embedded in this contact hole.

In addition, a manufacturing method of the liquid crystal display devicein accordance with this embodiment mode is almost similar to that ofEmbodiment Mode 2 except that the wiring for connecting 105 c is formedin the same step as the gate electrodes 105 a and 105 b. Hereinafter,common reference numerals are used for portions having similarstructures to Embodiment Mode 2 and description thereof is omitted.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 16 can be obtained. Notethat in each of the FFS-mode liquid crystal display devices shown inEmbodiment Modes 3, 6, 7, 9, and 12, and the IPS-mode liquid crystaldisplay devices shown in Embodiment Modes 4 and 5, a structure may beemployed in which the second gate wiring 180 and the second gateelectrodes 180 a and 180 b are formed in the same steps as the firstelectrode 101, and the gate wiring 105 is not formed and the gateelectrodes 105 a and 105 b are electrically connected to the second gatewiring 180 through the wiring for connecting 105 c, similarly to thisembodiment mode. Thus, an advantageous effect which is similar to thatof this embodiment mode can be obtained. In addition, in this embodimentmode, shapes of the second electrode 112 and the opening pattern 112 amay be the shapes shown in Embodiment Mode 4.

Embodiment Mode 18

FIG. 18A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 18 of theinvention. FIG. 18B is a cross-sectional view taken along a line E-F anda line G-H in FIG. 18A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 2 except that the thin filmtransistor 121 is a bottom-gate transistor. Accordingly, the contentsdescribed in Embodiment Mode 2 can also be applied to this embodimentmode. Hereinafter, common reference numerals are used for portionshaving similar structures to Embodiment Mode 2 and description thereofis omitted.

Accordingly, the contents described in Embodiment Modes 2 to 17 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In this embodiment, the gate electrodes 105 a and 105 b, the auxiliarywiring 106, and the gate wiring 105 are formed over the substrate 100,and the gate insulating film 104 is formed over each of the substrate100, the gate electrodes 105 a and 105 b, the auxiliary wiring 106, andthe gate wiring 105. In addition, the semiconductor film 103 is formedover the gate insulating film 104.

A manufacturing method of the liquid crystal display device inaccordance with this embodiment mode is as follows. First, the firstelectrode 101 and the insulating film 102 are formed over the substrate100. Subsequently, a conductive film is formed over the insulating film102.

The conductive film is formed of one element or a plurality of elementsselected from a group of aluminum (Al), tantalum (Ta), titanium (Ti),molybdenum (Mo), tungsten (W), neodymium (Nd), chromium (Cr), nickel(Ni), platinum (Pt), gold (Au), and silver (Ag), a compound includingone element or a plurality of the elements selected from the group as acomponent, a substance in which these compounds are combined, or acompound of silicon and one element or a plurality of the elementsselected from the group (silicide). Alternatively, silicon (Si) intowhich an n-type impurity is introduced may be used.

Subsequently, this conductive film is selectively removed by etchingusing a resist pattern. Thus, the gate electrodes 105 a and 1056, theauxiliary wiring 106, and the gate wiring 105 are formed over theinsulating film 102. After that, the resist pattern is removed.Subsequently, the gate insulating film 104 is formed.

Subsequently, a semiconductor film is formed over the gate insulatingfilm 104, and this semiconductor film is selectively removed by etchingusing a resist pattern. Thus, the semiconductor film 103 is formed.After that, the resist pattern is removed.

Subsequently, a resist pattern is formed over the semiconductor film103, and an impurity is added to the semiconductor film 103 by usingthis resist pattern as a mask. Thus, the impurity regions 103 a and 103b and an impurity region located between the gate electrodes 105 a and105 b are formed. Note that when the substrate 100 is formed of amaterial having a transmitting property such as glass, in the case offorming the resist pattern, the resist pattern is formed by lightexposure from a back side of the substrate 100 by using the gate wiringas a light-exposure pattern without using a light-exposure mask, in somecases. In this case, the number of steps can be reduced since thelight-exposure mask is not used, so that manufacturing cost can bereduced. In addition, since the resist pattern can be formed in aself-aligned manner, there is an advantage such that misalignment of theresist pattern is suppressed so that it is not necessary to considerthis misalignment. The subsequent steps are similar to those ofEmbodiment Mode 2.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. Note thatin each of the FFS-mode or IPS-mode liquid crystal display devices shownin Embodiment Modes 3 to 14, a thin film transistor for driving a pixelmay also be a bottom-gate thin film having a structure which is similarto this embodiment mode. In addition, in this embodiment mode, shapes ofthe second electrode 112 and the opening pattern 112 a may be the shapesshown in Embodiment Mode 4.

Embodiment Mode 19

FIG. 19A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 19 of theinvention. FIG. 19B is a cross-sectional view taken along a line I-J anda line K-L in FIG. 19A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 2 except for the followingpoints. A structure of a thin film transistor which controls the secondelectrode 112 serving as a pixel electrode is different; the secondinterlayer insulating film 111 is not provided; the second electrode 112and the first alignment film 113 are formed over the first interlayerinsulating film 107; the source wiring 108 and the conductive film forconnecting 109 are formed over the gate insulating film 104; and theconductive film for connecting 110 is formed in the same layer as thesecond electrode 112. Hereinafter, common reference numerals are usedfor portions having similar structures to Embodiment Mode 2 anddescription thereof is omitted.

Accordingly, the contents described in Embodiment Modes 2 to 18 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In this embodiment mode, a thin film transistor 122 is a bottom-gatetransistor, and the gate insulating film 104 is formed over the gatewiring 105. A semiconductor film 123 serving as a channel region isformed over the gate insulating film 104. For example, the semiconductorfilm 123 is an amorphous silicon film.

The semiconductor film 123 is electrically connected to the sourcewiring 108 with an n-type semiconductor film 124 a interposedtherebetween, and is electrically connected to the conductive film forconnecting 109 with an n-type semiconductor film 124 b interposedtherebetween. For example, each of the n-type semiconductor films 124 aand 124 b is a polysilicon film into which phosphorus or arsenic isintroduced and functions as a source or a drain.

A manufacturing method of the liquid crystal display device inaccordance with this embodiment mode is as follows. First, the firstelectrode 101 and the insulating film 102 are formed over the substrate100. Subsequently, a conductive film is formed over the insulating film102.

The conductive film is formed of one element or a plurality of elementsselected from a group of aluminum (Al), tantalum (Ta), titanium (Ti),molybdenum (Mo), tungsten (W), neodymium (Nd), chromium (Cr), nickel(Ni), platinum (Pt), gold (Au), and silver (Ag), a compound includingone element or a plurality of the elements selected from the group as acomponent, a substance in which these compounds are combined, or acompound of silicon and one element or a plurality of the elementsselected from the group (silicide). Alternatively, silicon (Si) intowhich an n-type impurity is introduced may be used.

Subsequently, this conductive film is selectively removed by etchingusing a resist pattern. Thus, the gate wiring 105 and the auxiliarywiring 106 are formed over the insulating film 102. After that, theresist pattern is removed. Subsequently, the gate insulating film 104 isformed.

Subsequently, a semiconductor film is formed over the gate insulatingfilm 104 by CVD, for example, and this semiconductor film is selectivelyremoved by etching using a resist pattern. Thus, the semiconductor film123 is formed. After that, the resist pattern is removed.

Subsequently, a semiconductor film is formed over the semiconductor film123 and the gate insulating film 104, and an n-type impurity is added tothis semiconductor film. Subsequently, this semiconductor film isselectively removed by etching using a resist pattern. Thus, the n-typesemiconductor films 124 a and 124 b are formed over the semiconductorfilm 123. After that, the resist pattern is removed.

Subsequently, a conductive film is formed over each of the semiconductorfilm 123, the n-type semiconductor films 124 a and 124 b, and the gateinsulating film 104, and this conductive film is selectively removed byetching using a resist pattern. Thus, the source wiring 108 and theconductive film for connecting 109 are formed. After that, the resistpattern is removed.

Subsequently, the first interlayer insulating film 107 is formed.Subsequently, a contact hole located over the conductive film forconnecting 109 is formed in the first interlayer insulating film 107. Inthis step, a contact hole located over the auxiliary wiring 106 isformed in the first interlayer insulating film 107 and the gateinsulating film 104, and a contact hole located over the first electrode101 is formed in the first interlayer insulating film 107, the gateinsulating film 104, and the insulating film 102.

Subsequently, a conductive film having a light-transmitting property(e.g., an ITO film, an IZO film, a ZnO film, or a Si film) is formedover the first interlayer insulating film 107 and in each contact hole,and this conductive film is selectively removed by etching using aresist pattern. Thus, the second electrode 112 and the conductive filmfor connecting 110 are formed. Subsequently, the first alignment film113 is formed over each of the first interlayer insulating film 107, thesecond electrode 112, and the conductive film for connecting 110. Thesubsequent steps are similar to the manufacturing method of the liquidcrystal display device in accordance with Embodiment Mode 2.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. Note thatthe source wiring 108 and the conductive film for connecting 109 mayalso be directly connected to the semiconductor film 123 without formingthe n-type semiconductor films 124 a and 124 b. In addition, a shape ofan opening pattern of the second electrode 112 may also be similar tothat of Embodiment Mode 5.

Further, in each of the FFS-mode liquid crystal display devices shown inEmbodiment Modes 6 to 18, and the IPS-mode liquid crystal display deviceshown in Embodiment Mod 5, the structure of the thin film transistor maybe changed similarly to this embodiment mode such that the secondinterlayer insulating film 111 is not provided, the second electrode 112and the first alignment film 113 are formed over the first interlayerinsulating film 107, the source wiring 108 and the conductive film forconnecting 109 are formed over the gate insulating film 104, and theconductive film for connecting 110 is formed in the same layer as thesecond electrode 112.

Embodiment Mode 20

FIG. 20A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 20 of theinvention. FIG. 20B is a cross-sectional view taken along a line M-N anda line O-P in FIG. 20A. This embodiment mode describes a structure whichis almost similar to that of Embodiment Mode 2 except for the followingpoints. The conductive film for connecting 110 electrically connects theconductive film for connecting 109 to the first electrode 101; thesecond electrode 112 is connected to the auxiliary wiring 106; and thesecond electrode 112 protrudes outside of the first electrode 101 whenseen from a direction which is perpendicular to the substrate 100. Thefirst electrode 101 functions as a pixel electrode and the secondelectrode 112 functions as a common electrode.

In addition, a manufacturing method of the liquid crystal display devicein accordance with this embodiment mode is similar to that of EmbodimentMode 19. Accordingly, the contents described in Embodiment Mode 19 canalso be applied to this embodiment mode.

Accordingly, the contents described in Embodiment Modes 2 to 19 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. Note thatthe source wiring 108 and the conductive film for connecting 109 mayalso be directly connected to the semiconductor film 123 without formingthe n-type semiconductor films 124 a and 124 b. In addition, in thisembodiment mode, a shape of an opening pattern of the second electrode112 may be similar to that of Embodiment Mode 4.

Further, an opening pattern may also be formed in the first electrode101. In this case, the liquid crystal display device in this embodimentmode becomes a device which controls an alignment direction of liquidcrystals by an IPS mode. Note that shapes of the first electrode 101,the second electrode 112, opening patterns of these electrodes are theshapes shown in Embodiment Mode 4, for example.

Embodiment Mode 21

FIG. 21A is a cross-sectional view showing a structure of an FFS-modeliquid crystal display device in accordance with Embodiment Mode 21 ofthe invention. This cross-sectional view shows a cross sectioncorresponding to a cross section taken along a line E-F and a line G-Hin FIG. 3A. This embodiment mode describes a structure which is almostsimilar to that of Embodiment Mode 3 except for the following points.The second interlayer insulating film 111 shown in FIG. 3B is notformed; the second electrode 112 is located over the first interlayerinsulating film 107; and a part of the second electrode 112 is locatedover the conductive film for connecting 110.

A manufacturing method of the liquid crystal display device inaccordance with this embodiment mode is almost similar to that ofEmbodiment Mode 3 except that the step of forming the second interlayerinsulating film 111 is omitted. Accordingly, the contents described inEmbodiment Mode 3 can also be applied to this embodiment mode.Hereinafter, common reference numerals are used for portions havingsimilar structures to Embodiment Mode 3 and description thereof isomitted.

Note that the second electrode 112 may also be formed at the same timeas the source wiring 108 or the like. That is, the second electrode 112may be formed of a similar material to and processed at the same time asthe source wiring 108 or the like. Accordingly, the step of forming thesecond electrode 112 by using an electrode having a light-transmittingproperty can be omitted, so that cost can be reduced.

Therefore, the second electrode 112 does not necessarily have alight-transmitting property. That is, the second electrode 112 mayreflect light.

Accordingly, the contents described in Embodiment Modes 2 to 20 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In accordance with this embodiment mode also, an advantageous which issimilar to that of Embodiment Mode 3 can be obtained. In addition, sincethe step of forming the second interlayer insulating film 111 isomitted, manufacturing cost can be reduced. Even when such a structureis employed, an interval between the first electrode 101 and the secondelectrode 112 can be sufficiently increased because the first electrode101 is provided below the insulating film 102 functioning as a basefilm, so that an appropriate electric field can be applied to the liquidcrystals 114.

Note that in each of the FFS-mode liquid crystal display devices shownin Embodiment Modes 2, and 6 to 18, and the IPS-mode liquid crystaldisplay devices shown in Embodiment Modes 4 and 5, the second electrode112 may also be provided over the first interlayer insulating film 107without forming the second interlayer insulating film 111, and a part ofthe second electrode 112 may also be located over the conductive filmfor connecting 110, similarly to this embodiment mode. An advantageouseffect which is similar to that of this embodiment mode can be obtainedalso in this case.

Embodiment Mode 22

FIG. 21B is a cross-sectional view showing a structure of an FFS-modeliquid crystal display device in accordance with Embodiment Mode 22 ofthe invention. This cross-sectional view shows a cross sectioncorresponding to a cross section taken along a line E-F and a line G-Hin FIG. 1A. This embodiment mode describes a structure which is almostsimilar to that of Embodiment Mode 21 except for the following points.All of the second electrode 112 is located over the first interlayerinsulating film 107; and a part of the conductive film for connecting110 is located over the second electrode 112.

A manufacturing method of the liquid crystal display device inaccordance with this embodiment mode is almost similar to that ofEmbodiment Mode 21 except that the source wiring 108, the conductivefilm for connecting 109, and the conductive film for connecting 110 areformed after the second electrode 112 is formed. Accordingly, thecontents described in Embodiment Mode 21 can also be applied to thisembodiment mode. Hereinafter, common reference numerals are used forportions having similar structures to Embodiment Mode 21 and descriptionthereof is omitted.

Accordingly, the contents described in Embodiment Modes 2 to 21 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

In accordance with this embodiment mode also, an advantageous which issimilar to that of Embodiment Mode 21 can be obtained. In addition,since the conductive film for connecting 110 is located over the secondelectrode 112, breaking of the second electrode 112 can be prevented.That is, when the second electrode 112 is formed over the conductivefilm for connecting 110 like Embodiment Mode 21, the conductive film forconnecting 110 is often formed to be thicker than the second electrode112, so that the second electrode 112 may cause breaking in an endportion of the conductive film for connecting 110. On the other hand, byforming the second electrode 112 below the conductive film forconnecting 110 like this embodiment mode, breaking of the secondelectrode 112 can be prevented. Note that since the conductive film forconnecting 110 is often formed to be thick as described above, breakingof the conductive film for connecting 110 is rare. In addition, sincethe step of forming the second interlayer insulating film 111 isomitted, manufacturing cost can be reduced. Even when such a structureis employed, an interval between the first electrode 101 and the secondelectrode 112 can be sufficiently increased because the first electrode101 is provided below the insulating film 102 functioning as a basefilm, so that an appropriate electric field can be applied to the liquidcrystals 114.

Note that in each of the FFS-mode liquid crystal display devices shownin Embodiment Modes 2, and 6 to 18, and the IPS-mode liquid crystaldisplay devices shown in Embodiment Modes 4 and 5, an advantageouseffect which is similar to that of this embodiment mode can be obtained,by providing the second electrode 112 over the first interlayerinsulating film 107 without forming the second interlayer insulatingfilm 111 and locating a part of the conductive film for connecting 110over the second electrode 112, similarly to this embodiment mode.

Embodiment Mode 23

FIG. 22 is a cross-sectional view showing a shape of an electrode of anFFS-mode liquid crystal display device in accordance with EmbodimentMode 23 of the invention. This cross-sectional view shows a crosssection corresponding to a cross section taken along a line E-F and aline G-H in FIG. 3A. This embodiment mode describes a structure which isalmost similar to that of Embodiment Mode 3 except that a metal film 110a is formed over the second interlayer insulating film 111, and thesecond electrode 112 and the conductive film for connecting 110 areelectrically connected with this metal film 110 a interposedtherebetween. Accordingly, the contents described in Embodiment Mode 3can also be applied to this embodiment mode. Hereinafter, commonreference numerals are used for portions having similar structures toEmbodiment Mode 3 and description thereof is omitted.

Accordingly, the contents described in Embodiment Modes 2 to 22 can alsobe applied to this embodiment mode.

Although description is made by using various drawings, one drawing ismade of various components. Accordingly, another structure can also beformed by combining each component in each drawing.

The metal film 110 a is electrically connected to the conductive filmfor connecting 110 by being partially embedded in a contact hole formedin the second interlayer insulating film 111. The second electrode 112is electrically connected to the metal film 110 a by being partiallylocated in the metal film 110 a.

A manufacturing method of the liquid crystal display device inaccordance with this embodiment mode is similar to that of EmbodimentMode 3 except that a step of forming the metal film 110 a exists betweenthe step of forming the contact hole in the second interlayer insulatingfilm 111 and the step of forming the second electrode 112. The metalfilm 110 a is formed by forming a metal film over the second interlayerinsulating film 111 and in the contact hole, and selectively removingthis metal film by etching using a resist pattern.

In accordance with this embodiment mode also, an advantageous which issimilar to that of Embodiment Mode 3 can be obtained.

Note that in the IPS-mode liquid crystal display device shown inEmbodiment Mode 4, the metal film 110 a may also be formed. In addition,in each of the FFS-mode liquid crystal display devices shown inEmbodiment Modes 2, and 6 to 18, and the IPS-mode liquid crystal displaydevice shown in Embodiment Mode 5, a metal film which is similar to themetal film 110 a may also be provided over the conductive film forconnecting 109, so that the conductive film for connecting 109 and thesecond electrode 112 are electrically connected through this metal film.

Embodiment Mode 24

FIG. 23 is a cross-sectional view showing a structure of a pixel portionof an FFS-mode liquid crystal display device in accordance withEmbodiment Mode 24 of the invention. The pixel portion of the liquidcrystal display device in accordance with This embodiment mode describesa structure which is almost similar to that of Embodiment Mode 2 exceptthat a red color filter 130 r, a blue color filter 1306, and a greencolor filter 130 g are provided instead of the first interlayerinsulating film 107 without providing a color filter on an oppositesubstrate 120 side. Accordingly, the contents described in EmbodimentModes 2 to 23 can also be applied to this embodiment mode. Hereinafter,common reference numerals are used for portions having similarstructures to Embodiment Mode 2 and description thereof is omitted. Notethat since the gate insulating film 104 is located between the colorfilters 130 r, 130 b, and 130 g, and the semiconductor film 103, thegate insulating film 104 also has a function of suppressing impuritydiffusion from each color filter to the semiconductor film 103.

Note that an insulating film of an inorganic material may also beprovided between the color filters and the gate electrodes 105 a and 105b. As an inorganic material, an insulating substance having oxygen ornitrogen such as silicon oxide (SiO_(x)), silicon nitride (SiN_(x)),silicon oxynitride (SiO_(x)N_(y):x>y), or silicon nitride oxide(SiN_(x)O_(y):x>y) can be used. In order to block impurity penetration,it is preferable to use a material including a large amount of nitrogen.

Note that colors of the color filters may be colors other than red,blue, and green or may be more than 3 colors, for example, four colorsor six colors may be used. For example, yellow, cyan, magenta, and/orwhite may be added. Further, not only the color filters but also a blackmatrix may be provided.

By providing the color filters over the substrate 100 in this manner, itis not necessary to precisely perform alignment to the oppositesubstrate 120, so that the liquid crystal display device can bemanufactured easily, cost is reduced, and a manufacturing yield isimproved.

A manufacturing method of the liquid crystal display device inaccordance with this embodiment mode is almost similar to those ofEmbodiment Modes 2 to 23 except that steps of forming the color filters130 r, 130 g, and 130 b exist instead of the step of forming the firstinterlayer insulating film 107. The color filters 130 r, 130 g, and 130b are formed by repeating the following steps three times: a step offorming a color filter layer; a step of forming a resist pattern overthe color filter layer; and a step of selectively dry etching the colorfilter layer by using the resist pattern as a mask. Alternatively, thecolor filters 130 r, 130 g, and 130 b are formed by using aphotosensitive material, pigment, or the like without using resist. Notethat a space is generated between the color filter layers, and thesecond interlayer insulating film 111 is embedded in this space.Alternatively, an inorganic material or an organic material is furtherstacked. Further alternatively, a black matrix or the like is stacked.In addition, the color filters 130 r, 130 g, and 130 b, or the blackmatrix can also be formed by using a droplet-discharge method (e.g., aninkjet method).

Therefore, the number of manufacturing steps of the liquid crystaldisplay device can be reduced. Since the color filters are provided onthe substrate 100 side, decrease in aperture ratio can be suppressedeven when misalignment to the opposite substrate is generated betweenthe substrate 100, compared with the case where the color filters areprovided for the opposite substrate. That is, a margin to misalignmentof the opposite substrate increases.

FIG. 24A is a plan view of the liquid crystal display device shown inFIG. 23. As shown in FIG. 24A, in this liquid crystal display device, asource line driver circuit 152 and a gate line driver circuit 154 whichare peripheral driver circuits are provided around a pixel portion 150.The red color filter 130 r may also be provided over each of the sourceline driver circuit 152 and the gate line driver circuit 154. Byproviding the color filter 130 r, light deterioration of an active layerof each thin film transistor included in the source line driver circuit152 and the gate line driver circuit 154 is prevented and planarizationis performed.

FIG. 24B is an enlarged view of a part of the pixel portion 150 (3rows×3 columns) in FIG. 24A. In the pixel portion 150, the red colorfilter 130 r, the blue color filter 130 b, and the green color filter130 g are arranged in stripes alternately. In addition, the red colorfilter 130 r is provided over a thin film transistor included in eachpixel.

Since a source wiring (not shown) and a gate wiring (not shown) areprovided so as to overlap with a space between the color filters,generation of light leakage is suppressed.

Since the color filter 130 r functions as a black matrix in this manner,the step of forming a black matrix, which is conventionally required,can also be omitted.

As described above, in accordance with this embodiment mode, anadvantageous effect which is similar to those of Embodiment Modes 2 to23 can be obtained. In addition, since the color filter 130 r, 130 b,and 130 g are provided instead of the first interlayer insulating film107, the number of the manufacturing steps of the liquid crystal displaydevice can be reduced. Further, decrease in aperture ratio can besuppressed even when misalignment to the opposite electrode isgenerated, compared with the case where the color filters are providedfor the opposite substrate. That is, a margin to misalignment of theopposite substrate increases.

Although the color filters are provided between the gate electrodes 105a and 105 b, and the source wiring 108 in FIG. 23, the invention is notlimited to this. The color filters may also be provided between thesource wiring 108 and the second electrode 112.

In addition, not only the color filters but also a black matrix may beprovided.

Note that an insulating film of an inorganic material may also beprovided between the color filters and the source wiring 108, or betweenthe color filters and the second electrode 112. As an inorganicmaterial, an insulating substance having oxygen or nitrogen such assilicon oxide (SiO_(x)), silicon nitride (SiN_(x)), silicon oxynitride(SiO_(x)N_(y):x>y), or silicon nitride oxide (SiN_(x)O_(y):x>y) can beused. In order to block impurity penetration, it is preferable to use amaterial including a large amount of nitrogen.

By providing the color filters or the black matrix below the secondelectrode 112 in this manner, a portion which is in contact with liquidcrystals or an alignment film can be planarized. By planarization,random orientation of liquid crystal molecules can be suppressed, lightleakage is suppressed, so that contrast can be improved.

Note that in each of the FFS-mode or IPS-mode liquid crystal displaydevices shown in Embodiment Modes 3 to 18, and 22, the color filters 130r, 130 b, and 130 g may be provided instead of the first interlayerinsulating film 107 or the second interlayer insulating film 111,similarly to this embodiment mode. An advantageous effect which issimilar to that of this embodiment mode can be obtained also in thiscase.

Embodiment Mode 25

FIG. 25A is a plan view showing a structure of an FFS-mode liquidcrystal display device in accordance with Embodiment Mode 25 of theinvention. FIG. 25B is an enlarged view showing a structure of a pixelportion in FIG. 25A. This embodiment mode describes a structure which isalmost similar to that of Embodiment Mode 24 except for layout of thecolor filters 130 r, 130 b, and 130 g. Accordingly, the contentsdescribed in Embodiment Mode 24 can also be applied to this embodimentmode. Hereinafter, common reference numerals are used for portionshaving similar structures to Embodiment Mode 24 and description thereofis omitted.

In this embodiment mode, the color filters 130 r, 130 b, and 130 g arearranged in matrix alternately per pixel. Specifically, the red colorfilter 130 r is provided so as to fill a space between the blue colorfilter 130 b and the green color filter 130 g. Although the color filter130 r is provided over the source line driver circuit 152 and the gateline driver circuit 154 which are peripheral driver circuits, the colorfilter 130 r is also provided in a space between each of the source linedriver circuit 152, the gate line driver circuit 154, and the pixelportion 150. Therefore, generation of a space between the color filterlayers is suppressed.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 24 can be obtained. Notethat after the first interlayer insulating film 107 is formed, the colorfilters 130 r, 130 b, and 130 g may also be provided instead of thesecond interlayer insulating film 111. An advantageous effect which issimilar to that of this embodiment mode can be obtained also in thiscase.

Note that in each of the FFS-mode or IPS-mode liquid crystal displaydevices shown in Embodiment Modes 3 to 18, and 23, the color filters 130r, 130 b, and 130 g may be provided instead of the first interlayerinsulating film 107 or the second interlayer insulating film 111,similarly to this embodiment mode. An advantageous effect which issimilar to that of this embodiment mode can be obtained also in thiscase.

Embodiment Mode 26

FIG. 26 is a cross-sectional view showing a structure of an FFS-modeliquid crystal display device in accordance with Embodiment Mode 26 ofthe invention. The liquid crystal display device in accordance with thisembodiment mode has a structure which is almost similar to that ofEmbodiment Mode 22 except that the color filters 130 r, 130 b, and 130 gare provided instead of the first interlayer insulating film 107. Layoutof the color filters 130 r, 130 b, and 130 g in this embodiment mode issimilar to the layout shown in Embodiment Mode 25. Accordingly, thecontents described in Embodiment Modes 22 and 25 can also be applied tothis embodiment mode. Hereinafter, common reference numerals are usedfor portions having similar structures to Embodiment Modes 22 and 25 anddescription thereof is omitted.

An advantageous effect which is similar to that of Embodiment Mode 25can be obtained in this embodiment mode. Note that in each of theFFS-mode liquid crystal display devices shown in Embodiment Mode 19 to21, the color filter 130 r, 130 b, and 130 g may also be providedinstead of the first interlayer insulating film 107, similarly to thisembodiment mode. An advantageous effect which is similar to that of thisembodiment mode can be obtained also in this case.

Note that the layout of the color filters 130 r, 130 b, and 130 g is notlimited to each layout shown in Embodiment Modes 23 to 25, and variouslayout such as triangle mosaic arrangement, RGBG four-pixelsarrangement, RGBW four-pixels arrangement, and the like can be used.Note also that the red color filter 130 r is preferably provided overthe active layer of the thin film transistor, also in such a case.

Embodiment Mode 27

FIGS. 27A to 27D are plan views each showing a shape of an electrode ofan FFS-mode liquid crystal display device in accordance with EmbodimentMode 27 of the invention. Since this embodiment mode describes astructure which is similar to Embodiment Mode 2 except for a shape ofthe second electrode 112, illustration is omitted except for the firstelectrode 101 and the second electrode 112.

In FIG. 27A, a plurality of slit-shaped opening patterns 112 d and 112 eare formed in the second electrode 112. The opening patterns 112 d and112 e are diagonal to the source wiring. Although the opening patterns112 d are formed in an upper half of the second electrode 112 in thedrawing and the opening patterns 112 e are formed in a lower half of thesecond electrode 112 in the drawing, they have different angles fromeach other.

In FIG. 27B, the second electrode 112 has a shape along circumference inwhich a plurality of electrodes, radii of which are different from eachother are provided in a concentric pattern and connected. In addition, aspace between the electrodes functions as an opening pattern.

In FIG. 27C, the second electrode 112 has a shape in which twocomb-shaped electrodes are provided so as to be reversed and makecomb-shaped portions alternate between them. In addition, a spacelocated between the comb-shaped portions functions as an openingpattern.

In FIG. 27D, the second electrode 112 has a comb-shape, and a spacelocated between comb-shaped portions functions as an opening pattern.

A manufacturing method of the liquid crystal display device inaccordance with this embodiment mode is almost similar to that ofEmbodiment Mode 2 in each case. Accordingly, the contents described inEmbodiment Mode 2 can also be applied to this embodiment mode.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 2 can be obtained. Note thatin each of the FFS-mode liquid crystal display devices shown inEmbodiment Modes 3, and 4 to 26, the shape of the second electrode 112may be any one of the shapes shown in FIGS. 27A to 27D.

Embodiment Mode 28

FIGS. 28A to 28D are plan views each showing a shape of an electrode ofan IPS-mode liquid crystal display device in accordance with EmbodimentMode 28 of the invention. Since this embodiment mode describes astructure which is similar to that of Embodiment Mode 4 except forshapes of the first electrode 101 and the second electrode 112,illustration is omitted except for the first electrode 101 and thesecond electrode 112.

In FIG. 28A, each of an opening pattern 101 b of the first electrode 101and an opening pattern 112 f of the second electrode 112 has a waveshape. The opening pattern 101 b is located below and around a region inwhich the opening pattern 112 f is not formed in the second electrode112.

In FIG. 28B, the first electrode 101 has a shape in which a circularopening pattern 101 c is provided in a center portion of a rectangularmain body portion; a plurality of electrodes along circumference, radiiof which are different from each other are provided in a patternconcentric with the opening pattern 101 c within the opening pattern 101c; and these electrodes along the circumference are connected to themain body portion by one linear electrode. The second electrode 112 hasa shape in which a circular opening pattern 112 g is provided in acenter portion of the rectangular main body portion; an electrode alongthe circumference is provided in a pattern concentric with the openingpattern 112 g within the opening pattern 112 g; and this electrode isconnected to the main body portion by one linear electrode. Note thatthe electrode along the circumference included in the second electrode112 may be provided in plural.

In addition, since the opening patterns 101 b and 112 g are concentricwith each other, each electrode along the circumference included in thefirst electrode 101 and the electrode along the circumference includedin the second electrode 112 are concentric with each other. Note thatsince the electrode along the circumference included in the firstelectrode 101 and the electrode along the circumference included in thesecond electrode 112 have different radii from each other, they arealternate and parallel to each other.

In FIG. 28C, the first electrode 101 has a shape in which a plurality oflinear electrodes which are extended longitudinally in the drawing areprovided alternately and in parallel to each other, and each of an upperend portion and a lower end portion of them is connected by a linearelectrode which is extended laterally in the drawing. In addition, thesecond electrode 112 has a comb shape, and a comb-shaped portion islocated in a space between the linear electrodes forming the firstelectrode 101.

In FIG. 28D, each of the first electrode 101 and the second electrode112 has a comb shape and they are reversed to each other. In addition,their comb-shaped portions are provided alternately.

A manufacturing method of the liquid crystal display device inaccordance with this embodiment mode is almost similar to that ofEmbodiment Mode 4 in each case. Accordingly, the contents described inEmbodiment Mode 4 can also be applied to this embodiment mode.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to that of Embodiment Mode 4 can be obtained. Note thatin the liquid crystal display devices in accordance with Embodiment Mode5, the shape of each of the first electrode 101 and the second electrode112 may be any one of the shapes shown in FIGS. 28A to 28D.

Embodiment Mode 29

FIG. 29 is a circuit diagram showing a circuit configuration of a liquidcrystal display device in accordance with Embodiment Mode 29 of theinvention. In the liquid crystal display device in accordance with thisembodiment mode, a plurality of pixels are arranged in matrix. Astructure of each pixel has a similar structure to each pixel includedin the liquid crystal display devices shown in Embodiment Modes 2 to 28except that a second auxiliary wiring 106 a which is extendedlongitudinally in the drawing is formed. Accordingly, the contentsdescribed in Embodiment Modes 2 to 28 can also be applied to thisembodiment mode. Hereinafter, common reference numerals are used forportions having similar structures to Embodiment Modes 2 to 28 anddescription thereof is omitted.

The second auxiliary wiring 106 a is formed in the same layer as theauxiliary wiring 106, and is electrically connected to the auxiliarywiring 106 at each of intersections with the auxiliary wiring 106.

In addition, the pixel includes a capacitor C_(S) and a capacitor C_(1S)which are connected to the thin film transistors 121 and 122. Thecapacitor C_(S) is a capacitor which is formed by the first electrode101, the second electrode 112 where the opening pattern is not formedand each insulating film located between the first electrode 101 and thesecond electrode 112. The capacitor C_(1S) is a capacitor which isformed by a portion which overlaps with the opening pattern of thesecond electrode 112 in the first electrode 101 and a portion locatedabove this portion. Since these capacitors are formed, storagecapacitance is increased.

In accordance with this embodiment mode also, an advantageous effectwhich is similar to those of Embodiment Modes 2 to 28 can be obtained.In addition, by providing the second auxiliary wiring 106 a, a potentialof the common electrode is easily held at the same value in all thepixels. Note that the liquid crystal display device in accordance withthis embodiment mode may employ an FFS mode or an IPS mode.

Embodiment Mode 30

Each of FIGS. 30A and 30B is a circuit diagram of a liquid crystaldisplay device in accordance with Embodiment Mode 30. The Liquid crystaldisplay device in accordance with this embodiment mode is an FFS-mode oran IPS-mode liquid crystal display device, and one pixel thereof isformed of a plurality of (e.g., 2) subpixels. A structure of eachsubpixel is a structure which is similar to that of any one of thepixels included in the liquid crystal display devices shown inEmbodiment Modes 2 to 28. Accordingly, the contents described inEmbodiment Modes 2 to 28 can also be applied to this embodiment mode.Hereinafter, common reference numerals are used for portions havingsimilar structures to Embodiment Modes 2 to 28 and description thereofis omitted.

In an example shown in FIG. 30A, a plurality of subpixels which form onepixel are electrically connected to one gate wiring 105, and areelectrically connected to the different source wirings 108 and thedifferent auxiliary wirings 106. The number of the source wirings 108 isthe same number as the subpixels (2 in FIG. 30A) every one pixel column.Therefore, a different signal can be transmitted to each subpixel.

In an example shown in FIG. 30B, a plurality of subpixels which form onepixel are electrically connected to the different gate wirings 105, andare electrically connected to one auxiliary wiring 106.

Note that each subpixel includes the capacitor C_(S) and the capacitorC_(1S). Since each of these capacitors has a structure which is similarto that of Embodiment Mode 29, description thereof is omitted.

In accordance with this embodiment mode, an advantageous effect which issimilar to those of Embodiment Modes 2 to 28 can be obtained. Inaddition, since one pixel is formed of a plurality of subpixels, aviewing angle can be further increased. Further, an advantageous effectcan be obtained in which the pixel is provided with redundancy, and anadvantageous effect can be obtained in which area gray scale display canbe performed.

Embodiment Mode 31

A manufacturing method of a liquid crystal display device in accordancewith Embodiment Mode 31 is described with reference to FIGS. 31A to 31E,FIGS. 32A to 32D, and FIGS. 33A and 33B. This embodiment mode is anexample of a manufacturing method of a liquid crystal display devicehaving the structure shown in Embodiment Mode 3. By using thismanufacturing method, degree of freedom of an interval between a commonelectrode and a pixel electrode is improved. Accordingly, since optimalvalues for an arrangement interval and width of an opening pattern ofthe pixel electrode change depending on a distance between the pixelelectrode and the common electrode, the size, the width, and theinterval of the opening pattern can be freely set. Then, a gradient ofan electric field applied between the electrodes can be controlled, sothat, for example, an electric field parallel to the substrate can beeasily increased. That is, since liquid crystal molecules which arealigned in parallel to the substrate (so-called homogeneous alignment)can be controlled in a direction parallel to the substrate in a displaydevice using liquid crystals, a viewing angle is widened by applying anoptimal electric field. Although an interlayer insulating film is asingle-layer structure in FIGS. 31A to 31E, FIGS. 32A to 32D, and FIGS.33A and 33B, it may be a two-layer structure.

First, as shown in FIG. 31A, a conductive film having alight-transmitting property is formed over a substrate 800. Thesubstrate 800 is a glass substrate, a quartz substrate, a substrateformed of an insulator such as alumina, a plastic substrate having heatresistance that can resist processing temperature of a post-process, asilicon substrate, or a metal substrate. Alternatively, the substrate800 may be a substrate in which an insulating film of silicon oxide,silicone nitride, or the like is formed on a surface of metal such asstainless, a semiconductor substrate, or the like. Note that in the caseof using a plastic substrate as the substrate 800, it is preferable touse a plastic substrate having a relatively high glass transition pointsuch as PC (polycarbonate), PES (polyethersulfone), PET (polyethyleneterephthalate), or PEN (polyethylene naphthalate).

In addition, the conductive film is, for example, an ITO film, or an IZO(Indium Zinc Oxide) film in which indium tin oxide or indium oxideincluding an Si element is mixed with zinc oxide (ZnO) at 2 to 20 wt %.

Subsequently, a photoresist film is formed over this conductive film,and this photoresist film is exposed and developed. Thus, a resistpattern is formed over the conductive film. Subsequently, the conductivefilm is etched by using this resist pattern as a mask. Thus, a firstelectrode 801 which is the pixel electrode is formed over the substrate800. After that, the resist pattern is removed.

Subsequently, an insulating film 802 is formed over the first electrode801 and the substrate 800. For example, the insulating film 802 is aninsulating film in which a silicon oxide (SiO_(x)) film is stacked on asilicon nitride (SiN_(x)) film; however, it may be another insulator(e.g., silicon oxynitride (SiO_(x)N_(y):x>y), or silicon nitride oxide(SiN_(x)O_(y):x>y).

Here, by performing nitriding on a surface of the insulating film 802formed of the silicon oxide film, the silicon oxynitride film, or thelike with high-density plasma, a nitride film may be formed on thesurface of insulating film 802.

For example, high-density plasma is generated by using a microwave of2.45 GHz, and has electron density of 1×10¹¹ to 1×10¹³/cm³, electrontemperature of 2 eV or less, and ion energy of 5 eV or less. Suchhigh-density plasma has low kinetic energy of active species, and canform a film with less plasma damage and fewer defects compared withconventional plasma treatment. A distance from an antenna generating amicrowave to the insulating film 802 is set to 20 to 80 mm, andpreferably, it is set to 20 to 60 mm.

The surface of the insulating film 802 can be nitrided by performing thehigh-density plasma treatment in a nitrogen atmosphere, such as in anatmosphere including nitrogen and rare gas or in an atmosphere includingnitrogen, hydrogen, and rare gas, or in an atmosphere including ammoniaand rare gas. Since such a nitride film can suppress impurity diffusionfrom the substrate 800 and can be formed to be extremely thin by thehigh-density plasma treatment, influence of stress on a semiconductorfilm formed thereover can be reduced.

Subsequently, as shown in FIG. 31B, a crystalline semiconductor film(e.g., a polysilicon film) is formed over the insulating film 802. As amethod of forming the crystalline semiconductor film, a method ofdirectly forming the crystalline semiconductor film over the insulatingfilm 802, and a method of forming an amorphous semiconductor film overthe insulating film 802, and then crystallizing the amorphoussemiconductor film can be given.

As a method for crystallizing the amorphous semiconductor film, a methodof laser light irradiation, a method of thermal crystallization using anelement which promotes crystallization of a semiconductor film (e.g., ametal element such as nickel), or a method of laser light irradiationafter thermal crystallization using an element which promotescrystallization of the semiconductor film can be used. Needless to say,a method of thermal crystallization of the amorphous semiconductor filmwithout using the above-described element can also be used; however, itis limited to the case of a substrate which can withstand hightemperature such as a quartz substrate or a silicon wafer.

When laser irradiation is used, a continuous wave laser beam (a CW laserbeam) or a pulsed laser beam can be used. As a laser beam which can beused here, laser beams which are emitted from one laser or a pluralityof lasers from a gas laser such as an Ar laser, a Kr laser, or anexcimer laser, a laser using a medium in which one element or aplurality of elements of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta is added asa dopnat to single crystal of YAG, YVO₄, forsterite (Mg₂SiO₄), YAlO₃, orGdVO₄, or polycrystal (ceramic) of YAG Y₂O₃, YVO₄, YAlO₃, or GdVO₄, aglass laser, a ruby laser, an alexandrite laser, a Ti:sapphire laser, acopper vapor laser, or a gold vapor laser can be given. By laser beamirradiation with a fundamental wave of such a laser beam and a secondharmonic wave to a fourth harmonic wave of the fundamental wave of sucha laser beam, crystals each having a large particle size can beobtained. For example, a second harmonic wave (532 nm) or a thirdharmonic wave (355 nm) of an Nd:YVO₄ laser (having a fundamental wave of1064 nm) can be used. At this time, power density of the laser isnecessary to be about 0.01 to 100 MW/cm² (preferably, 0.1 to 10 MW/cm²).Irradiation is performed by setting the scan speed at about 10 to 2000cm/sec.

Note that the laser using a medium in which one element or a pluralityof elements of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta is added as a dopnatinto single crystal of YAG, YVO₄, forsterite (Mg₂SiO₄), YAlO₃, or GdVO₄,or polycrystal (ceramic) of YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄; an Ar ionlaser; or the Ti:sapphire laser can be continuously oscillated, and canalso be pulsed oscillated with a repetition rate of 10 MHz or more byperforming a Q-switch operation, mode locking, or the like. When thelaser beam is emitted with the repetition rate of 10 MHz or more, asemiconductor film is irradiated with the next pulse during the periodin which the semiconductor film is melted by the laser beam andsolidified. Accordingly, a solid-fluid interface can be continuouslymoved in the semiconductor film so that crystal grains which have growncontinuously in the scan direction can be obtained, unlike the case ofusing a pulsed laser with a low repetition rate.

When ceramic (a polycrystal) is used as a medium, the medium can beformed in a free shape in a short time and at low cost. When a singlecrystal is used, a columnar medium having a diameter of several mm and alength of several tens mm is usually used; however, when ceramic isused, a larger medium can be made.

Since concentration of a dopant such as Nd or Yb in a medium whichdirectly contributes to light emission cannot be greatly changed ineither the single crystal or the polycrystal, there is a limitation onimprovement in output of a laser by increasing the concentration of thedopant to some extent. However, in the case of ceramic, significantimprovement in output can be expected because the size of the medium canbe extremely increased compared with the single crystal.

Further, in the case of ceramic, a medium having a parallelepiped shapeor a rectangular parallelepiped shape can be easily formed. When amedium having such a shape is used and emitted light is made travel in azigzag manner inside the medium, a path of the emitted light can be madelong. Therefore, amplification is increased so that a laser beam can beemitted with high output. Furthermore, since a cross section of a laserbeam emitted from the medium having such a shape is a quadrangularshape, it has an advantage in being shaped into a linear beam comparedwith a circular beam. By shaping laser beam emitted in this manner withan optical system, a linear beam having a length of 1 mm or less on alateral side and a length of several mm to several m on a longitudinalside can be easily obtained. Moreover, when the medium is uniformlyirradiated with excited light, energy distribution of the linear beam isuniform in a longitudinal direction.

By irradiating the semiconductor film with this linear beam, the wholesurface of the semiconductor film can be annealed more uniformly. Whenuniform annealing is needed to opposite ends of the linear beam, adevice such that a portion where energy is attenuated is shielded byproviding slits in the opposite ends is needed.

When the semiconductor film is annealed by using the linear beam havinguniform intensity which can be obtained in this manner and an electronicdevice is manufactured by using this semiconductor film, characteristicsof the electronic device are excellent and uniform.

As a method of thermal crystallization by using an element whichpromotes crystallization of an amorphous semiconductor film, a techniquedisclosed in Japanese Published Patent Application No. H08-78329 can beused. The technique disclosed in the Patent Application is as follows. Ametal element which promotes crystallization is added to an amorphoussemiconductor film (also called an amorphous silicon film) and heattreatment is performed thereto, so that an amorphous semiconductor filmis crystallized from an added region as a starting point.

Alternatively, the amorphous semiconductor film can be crystallized byperforming intense light irradiation instead of heat treatment. In thiscase, any one of infrared light, visible light, and ultraviolet light,or a combination thereof can be used. Typically, light emitted from ahalogen lamp, a metal halide lamp, a xenon arc lamp, a carbon arc lamp,a high pressure sodium lamp, or high pressure mercury lamp is used. Alamp light source is turned on for 1 to 60 seconds, preferably, 30 to 60seconds, and this operation is repeated 1 to 10 times, preferably, 2 to6 times. Although emission intensity of the lamp light source is set asappropriate, it is set so that a semiconductor film is heated at around600 to 1000° C. for a moment. Note that heat treatment for releasinghydrogen included in an amorphous semiconductor film having an amorphousstructure may be performed before performing intense light irradiation,if necessary. In addition, the amorphous semiconductor film may becrystallized by performing both heat treatment and intense lightirradiation.

In order to increase degree of crystallinity (a ratio of a crystallinecomponent in a total volume of a film) of a crystalline semiconductorfilm after heat treatment to repair a defect left in a crystal grain,the crystalline semiconductor film may be irradiated with laser light inan atmosphere or an oxygen atmosphere. As laser light, theabove-described one can be used.

In addition, it is necessary to remove the added element from thecrystalline semiconductor film, and a method thereof is described below.First, a barrier layer formed of an oxide film (called chemical oxide)is formed having a thickness of 1 nm to 10 nm on a surface of thecrystalline semiconductor film by processing the surface of thecrystalline semiconductor film with a solution including ozone(typically, ozone water). The barrier layer functions as an etchingstopper when only a gettering layer is selectively removed in a laterstep.

Subsequently, the gettering layer including a rare gas element is formedover the barrier layer as a gettering site. Here, a semiconductor filmincluding a rare gas element is formed as the gettering layer by CVD orsputtering. When the gettering layer is formed, a sputtering conditionis controlled as appropriate so that the rare gas element is added tothe gettering layer. As the rare gas element, one element or a pluralityof elements selected from helium (He), neon (Ne), argon (Ar), krypton(Kr), and xenon (Xe) is used.

In the case where the gettering layer is formed by using source gasincluding phosphorus which is an impurity element is used or by using atarget including phosphorus, gettering can be performed by using acoulomb force of phosphorus as well as gettering by the rare gaselement. In addition, since a metal element (e.g., nickel) tends to moveto a region having high oxygen concentration in gettering, it ispreferable that oxygen concentration included in the gettering layer be,for example, 5×10¹⁸ cm⁻³ or more.

Subsequently, gettering of the metal element (e.g., nickel) is performedby performing heat treatment (e.g., thermal treatment or intense lightirradiation) to the crystalline semiconductor film, the barrier layer,and the gettering layer, and the metal element in the crystallinesemiconductor film is decreased in its concentration or removed.

Subsequently, etching is performed by a known etching method using thebarrier layer as an etching stopper, and only the gettering layer isselectively removed. After that, the barrier layer formed of the oxidefilm is removed by an etchant including, for example, hydrofluoric acid.

Here, an impurity ion may also be added considering thresholdcharacteristics of a TFT manufactured.

Subsequently, a photoresist film (not shown) is applied over thecrystalline semiconductor film by an application method, and thisphotoresist film is exposed and developed. The application method meansa spin coating method, a spray method, a screen printing method, a paintmethod, or the like. Thus, a resist pattern is formed over thecrystalline semiconductor film. Subsequently, the crystallinesemiconductor film is etched by using this resist pattern as a mask.Thus, a crystalline semiconductor film 803 is formed over the insulatingfilm 802.

Subsequently, after a surface of the crystalline semiconductor film 803is washed by an etchant including hydrofluoric acid, a gate insulatingfilm 804 is formed having a thickness of 10 nm to 200 nm over thecrystalline semiconductor film 803. The gate insulating film 804 isformed of an insulating film including silicon as a main component suchas a silicon oxide film, a silicon nitride film, a silicon oxynitridefilm, a silicon nitride oxide film, or the like. In addition, the gateinsulating film 804 may be a single layer or a stacked-layer film. Notethat the gate insulating film 804 is formed also over the insulatingfilm 802.

Subsequently, as shown in FIG. 31C, after the gate insulating film 804is washed, a first conductive film and a second conductive film aresequentially formed over the gate insulating film 804. For example, thefirst conductive film is a tungsten film and the second conductive filmis a tantalum nitride film.

Subsequently, a photoresist film (not shown) is applied over the secondconductive film, and this photoresist film is exposed and developed.Thus, a resist pattern is formed over the second conductive film.Subsequently, the first conductive film and the second conductive filmare etched in a first condition, and the second conductive film isetched in a second condition by using this resist pattern as a mask.Thus, first gate electrodes 805 a and 805 b, and second gate electrodes806 a and 806 b are formed over the crystalline semiconductor film 803.The first gate electrodes 805 a and 805 b are separated from each other.The second gate electrode 806 a is located over the first gate electrode805 a, and the second gate electrode 806 b is located over the firstgate electrode 805 b. A tilt angle of each side surface of the firstgate electrodes 805 a and 805 b is more gradual than a tilt angle ofeach side surface of the second gate electrodes 806 a and 806 b.

In addition, by this etching treatment, a first wiring 807 and a secondwiring 808 located over the first wiring 807 are formed near the firstelectrode 801. Here, it is preferable that each gate electrode and eachwiring described above be led so that corners thereof are rounded whenseen from a direction which is perpendicular to the substrate 800. Byrounding the corners, the case where dust or the like remains at thecorners of the wiring can be prevented, so that a defect caused by dustcan be suppressed to improve a yield. After that, the photoresist filmis removed.

Subsequently, as shown in FIG. 31D, an impurity element 809 (e.g.,phosphorus) of a first conductivity type (e.g., n-type conductivity) isadded to the crystalline semiconductor film 803 using the first gateelectrodes 805 a and 805 b, and the second gate electrodes 806 a and 806b as masks. Thus, first impurity regions 810 a, 810 b, and 810 c areformed in the crystalline semiconductor film 803. The first impurityregion 810 a is located in a region serving as a source of the thin filmtransistor. The first impurity region 810 c is located in a regionserving as a drain of the thin film transistor. The first impurityregion 810 b is located between the first gate electrodes 805 a and 805b.

Subsequently, as shown in FIG. 31E, a photoresist film is applied so asto cover the whole surface of each of the first gate electrodes 805 aand 805 b and the second gate electrodes 806 a and 806 b, and thisphotoresist film is exposed and developed. Thus, a top face and theperiphery of each of the first gate electrode 805 a and the second gateelectrode 806 a, and a top face and the periphery of each of the firstgate electrode 805 b and the second gate electrode 806 b are coveredwith resist patterns 812 a and 812 b. Subsequently, an impurity element811 of the first conductivity type (e.g., phosphorus) is added to thecrystalline semiconductor film 803 by using the resist patterns 812 aand 812 b as masks. Thus, the impurity element 811 of the firstconductivity type is added again to a part of each of the first impurityregions 810 a, 810 b, and 810 c, so that second impurity regions 813 a,813 b, and 813 c are formed. Note that the other parts of each of thefirst impurity regions 810 a, 810 b, and 810 c are left as thirdimpurity regions 814 a, 814 b, 814 c, and 814 d.

After that, as shown in FIG. 32A, the resist patterns 812 a and 812 bare removed. Subsequently, an insulating film covering almost the wholesurface (not shown) is formed. This insulating film is, for example, asilicon oxide film, and is formed by plasma CVD.

Subsequently, by performing heat treatment to the crystallinesemiconductor film 803, the impurity elements which are added areactivated. This heat treatment is a rapid thermal annealing method (anRTA method) using a lamp light source, a method of a YAG laser or anexcimer laser irradiation from a back side, or heat treatment using afurnace, or treatment by a method combining a plurality of thesemethods.

By the above-described heat treatment, the element which is used as acatalyzer (e.g., a metal element such as nickel) when the crystallinesemiconductor film 803 is crystallized is gettered by the secondimpurity regions 813 a, 813 b, and 813 c including the highconcentration impurities (e.g., phosphorus), and nickel concentrationmainly in a portion serving as a channel formation region is reduced inthe crystalline semiconductor film 803, as well as activating theimpurity element. Accordingly, crystallinity of the channel formationregion is improved. Therefore, an off-current value of the TFT islowered and high electron field-effect mobility can be obtained. A TFThaving excellent properties can be obtained in this manner.

Subsequently, an insulating film 815 is formed so as to cover thesurface of the crystalline semiconductor film 803. The insulating film815 is, for example, a silicon nitride film, and is formed by plasmaCVD. Subsequently, a planarizing film serving as an interlayerinsulating film 816 is formed over the insulating film 815. As theinterlayer insulating film 816, an inorganic material having alight-transmitting property (e.g., silicon oxide, silicon nitride, orsilicon nitride including oxygen), a photosensitive ornon-photosensitive organic material (e.g., polyimide, acryl, polyamide,polyimide amide, resist or benzocyclobutene), a stacked layer of such amaterial, or the like is used. In addition, as another film having alight-transmitting property which is used as the planarizing film, aninsulating film formed of an SiOx film including an alkyl group obtainedby the application method, such as an insulating film formed by usingsilica glass, an alkylsiloxane polymer, an alkylsilsesquioxane polymer,a hydrogen silsesquioxane polymer, a hydrogen alkylsilsesquioxanepolymer, or the like can be used. As examples of a siloxane-basedpolymer, coating insulating film materials such as PSB-K1 and PSB-K31(products of Toray industries, Inc.) and ZRS-5PH (a product of Catalysts& Chemicals Industries Co., Ltd.) can be given. The interlayerinsulating film 816 may be a single-layer film or a multi-layer film.

Subsequently, a photoresist film (not shown) is applied over theinterlayer insulating film 816, and this photoresist film is exposed anddeveloped. Thus, a resist pattern is formed over the interlayerinsulating film 816. Subsequently, the interlayer insulating film 816,the insulating film 815, and the gate insulating film 804 are etched byusing this resist pattern as a mask. Thus, contact holes 817 a, 817 b,817 c, and 817 d are formed in the interlayer insulating film 816, theinsulating film 815, and the gate insulating film 804. The contact hole817 a is located over the second impurity region 813 a which is thesource of the transistor, and the contact hole 817 b is located over thesecond impurity region 813 c which is the drain of the transistor. Thecontact hole 817 c is located over the first electrode 801, and thecontact hole 817 d is located over the second wiring 808. After that,the resist pattern is removed.

Subsequently, as shown in FIG. 32B, a first conductive film 818 isformed in each of the contact holes 817 a, 817 b, 817 c, and 817 d andover the interlayer insulating film 816. In addition, the firstconductive film 818 is a conductive film having a light-transmittingproperty, such as an ITO film, or an IZO (Indium Zinc Oxide) film inwhich indium tin oxide or indium oxide including an Si element is mixedwith zinc oxide (ZnO) at 2 to 20 wt %. Subsequently, a second conductivefilm 819 is formed over the first conductive film 818. The secondconductive film 819 is, for example, a metal film.

Subsequently, a photoresist film 820 is applied over the secondconductive film 819. Subsequently, a reticle 840 is provided above thephotoresist film 820. As for the reticle 840, semi-transmissive filmpatterns 842 a, 842 b, 842 c, 842 d are formed over a glass substrate,and light-shielding patterns 841 a, 841 b, and 841 c are formed over apart of each of the semi-transmissive film patterns 842 a, 842 b, 842 c,and 842 d. The semi-transmissive film pattern 842 a and thelight-shielding pattern 841 a are located above the contact hole 817 a;the semi-transmissive film pattern 842 b and the light-shielding pattern841 b are located above the contact hole 817 b and the contact hole 817c; the semi-transmissive film pattern 842 c and the light-shieldingpattern 841 c are located above the contact hole 817 d; and thesemi-transmissive film pattern 842 d is located above the firstelectrode 801.

Subsequently, the photoresist film 820 is exposed by using the reticle840 as a mask. Thus, the photoresist film 820 is exposed to light exceptfor a portion located below the light-shielding patterns 841 a, 841 b,and 841 c and lower layer portions located near the second conductivefilm 819 which is below a portion where the semi-transmissive filmpatterns 842 a, 842 b, 842 c, and 842 d and the light-shielding patterns841 a, 841 b, and 841 c are not overlapped. Note that reference numerals821 a, 821 b, 821 c, and 821 d are used for the portions which are notexposed to light.

Subsequently, as shown in FIG. 32C, the photoresist film 820 isdeveloped. Thus, the portions which are exposed to light in thephotoresist film 820 are removed, and resist patterns 822 a, 822 b, 822c, and 822 d are formed. The resist pattern 822 a is located over thecontact hole 817 a. The resist pattern 822 b is located over each of thecontact hole 817 b and the contact hole 817 c and therebetween. Theresist pattern 822 c is located over and around the contact hole 817 d.The resist pattern 822 d is located over the first electrode 801. Notethat a portion other than a position over the contact hole 817 d in theresist pattern 822 c, and the resist pattern 822 d are thinner thanother resist patterns.

Subsequently, as shown in FIG. 32D, the first conductive film 818 andthe second conductive film 819 are etched by using the resist patterns822 a, 822 b, 822 c, and 822 d as masks. Thus, the first conductive film818 and the second conductive film 819 are removed from regions whichare not covered with the resist patterns 822 a, 822 b, 822 c, and 822 d.

In addition, since the resist patterns 822 a, 822 b, 822 c, and 822 dare also gradually etched, thin portions of the resist patterns(specifically, the portion other than the portion over the contact hole817 d in the resist pattern 822 c, and the resist pattern 822 d) areremoved during etching treatment. Therefore, in a portion located beloweach of the portion other than the portion over the contact hole 817 din the resist pattern 822 c, and the resist pattern 822 d, the secondconductive film 819 is removed and only the first conductive film 818 isleft. After that, the resist patterns 822 a, 822 b, and 822 c areremoved.

In this manner, source wirings 823 a and 824 a, drain wirings 823 b and824 b, a conductive film for connecting 824 c, and a second electrode828 which is a common electrode are formed by one resist pattern and oneetching treatment. The source wirings 823 a and 824 a, and the drainwirings 823 b and 824 b form a thin film transistor 825, with thecrystalline semiconductor film 803, each impurity region formed in thecrystalline semiconductor film 803, the gate insulating film 804, thefirst gate electrodes 805 a and 805 b, and the second gate electrodes806 a and 806 b. In addition, the drain wirings 823 b and 824 belectrically connect the impurity region 813 c serving as the drain tothe first electrode 801. The second electrode 828 is electricallyconnected to the second wiring 808 by being partially embedded in thecontact hole 817 d. The conductive film for connecting 824 c is locatedover the second electrode 828 located over the contact hole 817 d.

After that, a first alignment film 826 is formed. In this manner, anactive matrix substrate is formed. Note that by the treatment shown inFIGS. 31A to 31E, and FIGS. 32A to 32D, thin film transistors 827 and829 (shown in FIG. 33B) are also formed in a gate signal line drivercircuit region 854 of a liquid crystal display device shown in FIGS. 33Aand 33B. Further, by the treatment shown in FIGS. 31B to 31D, a firstterminal electrode 838 a and a second terminal electrode 838 b (shown inFIG. 33B) which connect the active matrix substrate to the outside areformed.

After that, as shown in a plan view in FIG. 33A and a cross-sectionalview taken along a line K-L in FIG. 33B, an organic resin film such asan acryl resin film is formed over the active matrix substrate, and thisorganic resin film is selectively removed by etching using a resistpattern. Thus, a columnar spacer 833 is formed over the active matrixsubstrate. Subsequently, liquid crystals are dropped on the activematrix substrate after a sealant 834 is formed in a sealing region 853.Before dropping the liquid crystal, a protective film which prevents thesealant and the liquid crystals from reacting with each other may beformed.

After that, an opposite substrate 830 over which a color filter 832 anda second alignment film 831 are formed is provided in a positionopposite to the active matrix substrate, and these two substrate areattached together with the sealant 834. At this time, the active matrixsubstrate and the opposite substrate 830 are attached together with auniform distance by the spacer 833. Subsequently, a space between thesubstrates is completely sealed by using a sealant (not shown). In thismanner, the liquid crystals are sealed between the active matrixsubstrate and the opposite substrate.

Subsequently, either one or both of the active matrix substrate and theopposite substrate is/are separated in a desired shape, if necessary.Further, polarizing plates 835 a and 835 b are provided. Subsequently, aflexible printed circuit (hereinafter described as an FPC) 837 isconnected to the second terminal electrode 838 b provided in an externalterminal connecting region 852 through an anisotropic conductive film836.

A structure of a liquid crystal module formed in this manner isdescribed below. A pixel region 856 is provided in the center of theactive matrix substrate. A plurality of pixels are formed in the pixelregion 856. In FIG. 33A, a gate signal line driver circuit region 854for driving each gate signal line is provided above and below the pixelregion 856. In addition, a source signal line driver circuit region 857for driving each source signal line is provided in a region between thepixel region 856 and the FPC 837. The gate signal line driver circuitregion 854 may be provided only on one side, which can be selectedappropriately considering a substrate size or the like in the liquidcrystal module. However, it is preferable that the gate signal linedriver circuit regions 854 be symmetrically provided with the pixelregion 856 interposed therebetween when operation reliability, drivingefficiency, or the like of the circuit is considered. Further, input ofa signal to each driver circuit is performed by the FPC 837.

In accordance with this embodiment mode also, an effect which is thesame as that of Embodiment Mode 3 can be obtained.

Embodiment Mode 32

A liquid crystal display module in accordance with Embodiment Mode 32 isdescribed with reference to FIGS. 34A and 34B, and FIGS. 35A and 35B. Ineach drawing, a structure of a pixel portion 930 is similar to thestructure of the pixel region 856 shown in Embodiment Mode 31, in whicha plurality of pixels are formed over the substrate 100.

FIG. 34A is a schematic plan view of the liquid crystal display module,and FIG. 34B is a diagram showing a circuit configuration of a sourcedriver 910. In an example shown in FIGS. 34A and 34B, both of a gatedriver 920 and the source driver 910 are formed over the same substrate100 as the pixel portion 930, as shown in FIG. 34A. The source driver910 includes a plurality of thin film transistors 912 for controlling asource signal line to which an input video signal is transmitted, and ashift register 911 for controlling the plurality of thin filmtransistors 912, as shown in FIG. 34B.

FIG. 35A is a schematic plan view of the liquid crystal display module,and FIG. 35B is a diagram showing a circuit configuration of a sourcedriver. In an example shown in FIGS. 35A and 35B, the source driverincludes a thin film transistor group 940 formed over the substrate 100,and an IC 950 which is separately formed from the substrate 100, asshown in FIG. 35A. The IC 950 and the thin film transistor group 940 areelectrically connected with, for example, an FPC 960.

The IC 950 is, for example, formed by using a single crystalline siliconsubstrate, and controls the thin film transistor group 940 and inputs avideo signal to the thin film transistor group 940. The thin filmtransistor group 940 controls a source signal line to which a videosignal is transmitted based on a control signal from the IC 950.

Also by the liquid crystal display module in accordance with EmbodimentMode 32, an effect which is the same as that of Embodiment Mode 3 can beobtained.

Embodiment Mode 33

FIGS. 38A and 38B are cross-sectional views each showing a structure ofa light-emitting device using the invention. In this embodiment, anexample is shown in which the structure of the invention is combinedwith a self light-emitting element (e.g., an EL element) is described.

FIG. 38A is an example of a light-emitting device combining thestructure of the invention with a thin-film EL element. The thin-film ELelement includes a light-emitting layer formed of a thin film of alight-emitting material, and light emission can be obtained by collisionexcitation of a luminescent center or a host material by electronsaccelerated with a high electric field.

As a mechanism of light emission, there are donor-acceptor recombinationtype light emission utilizing a donor level and an acceptor level, andlocalized-type light emission utilizing inner-shell electron transitionof a metal ion. In general, in many cases, a thin-film EL element haslocalized-type light emission and a dispersion-type EL element hasdonor-acceptor recombination type light emission.

A specific structure is described below. FIG. 38A has a structure usinga top-gate thin film transistor 221, and is similar to that of theliquid crystal display device in accordance with Embodiment Mode 1 inthat a first electrode 201 and a second electrode 212 are used. That is,the first electrode 201 is formed over a substrate 200; an insulatingfilm 202 is formed over the substrate 200 and the first electrode 201;and the thin film transistor 221 is formed over the insulating film 202.In addition, interlayer insulating films 206 and 207 are formed over thethin film transistor 221, and the second electrode 212 is formed overthe interlayer insulating film 207. A slit is formed in the secondelectrode 212. Note that a slit may also be formed in the firstelectrode 201. In this embodiment mode, a layer 214 including alight-emitting material is provided over the second electrode 212.

The substrate 200, the first electrode 201, the insulating film 202, thethin film transistor 221, the interlayer insulating films 206 and 207,and the second electrode 212 are formed by steps which are similar tothose of Embodiment Mode 2. Next, a dielectric 213 is formed over thesecond electrode 212, and the layer 214 including the light-emittingmaterial may be provided over the dielectric 213. However, the inventionis not limited this structure, and the dielectric 213 is not necessarilyprovided. When the dielectric 213 is not formed, each of the interlayerinsulating films 206 and 207 functions as a dielectric. Further, asecond substrate 220 is provided over the layer 214 including thelight-emitting material with a protective layer 215 interposedtherebetween.

A light-emitting material includes a host material and a luminescentcenter. As a luminescent center of localized-type light emission,manganese (Mn), copper (Cu) samarium (Sm), terbium (Tb), erbium (Er),thulium (Tm), europium (Eu), cerium (Ce), praseodymium (Pr), or the likecan be used. Note that a halogen element such as fluorine (F) orchlorine (Cl) may be added as charge compensation.

As a light-emission center of donor-acceptor recombination type lightemission, a light-emitting material including a first impurity elementwhich forms a donor level and a second impurity element which forms anacceptor level can be used. As the first impurity element, for example,fluorine (F), chlorine (Cl), aluminum (Al), or the like can be used. Asthe second impurity element, for example, copper (Cu), silver (Ag), orthe like can be used.

As a host material used for a light-emitting material, hydrosulfide,oxide, or nitride can be used. As hydrosulfide, for example, zincsulfide (ZnS), cadmium sulfide (CdS), calcium sulfide (CaS), yttriumsulfide (Y₂S₃), gallium sulfide (Ga₂S₃), strontium sulfide (SrS), bariumsulfide (BaS), or the like can be used. As oxide, for example, zincoxide (ZnO), yttrium oxide (Y₂O₃), or the like can be used.

As nitride, for example, aluminum nitride (AlN), gallium nitride (GaN),indium nitride (InN), or the like can be used. Further, zinc selenide(ZnSe), zinc telluride (ZnTe), or the like can also be used, and aternary mixed crystal such as calcium sulfide-gallium (CaGa₂S₄),strontium sulfide-gallium (SrGa₂S₄), or barium sulfide-gallium (BaGa₂S₄)may also be used.

In many cases, a thin-film EL element has localized-type light emissionand a dispersion-type EL element has donor-acceptor recombination typelight emission. In the case of the structure in FIG. 38A, it ispreferable that a light-emitting material using a luminescent centerserving as localized light emission (e.g., ZnS:Mn, ZnS:Cu, or Cl) beused.

Next, FIG. 38B shows an example of a light-emitting device combining thestructure of the invention with a dispersion-type EL element. Thedispersion-type EL element includes a light-emitting layer in whichparticles of a light-emitting material are dispersed in a binder, andlight emission can be obtained by collision excitation of a luminescentcenter or a host material by electrons accelerated with a high electricfield, similarly to the thin-film EL element. In the case of thedispersion-type EL element, a layer 224 including the light-emittingmaterial is provided so as to be in contact with the second electrode212.

As a light-emitting material which is dispersed in a binder, theabove-described light-emitting material can be used similarly to thethin-film type EL element. Note that in the case of the dispersion-typeEL element, it is preferable that a light-emitting material using aluminescent center serving as donor-acceptor recombination type lightemission (e.g., ZnS:Ag, Cl, ZnS:Cu, or Al) be used. In addition, thelight-emitting material is not limited to an inorganic material, and alight-emitting material using an organic material (e.g., rbrene, or9,10-diphenylanthracene) may also be used.

As a binder which can be used for the dispersion-type EL element, anorganic material or an inorganic material can be used, or a mixedmaterial of an organic material and an inorganic material may be used.As an organic material, a resin such as a polyethylene, polypropylene, apolystyrene-based resin, a silicone resin, an epoxy resin, or vinylidenefluoride, or a polymer having a comparatively high dielectric constantlike a cyanoethyl cellulose-based resin can be used. In addition, aheat-resistant molecule such as aromatic polyamide or polybenzimidazole,or a siloxane resin may also be used.

Further, a resin material such as a vinyl resin, e.g., polyvinyl alcoholor polyvinyl butyral, a phenol resin, a novolac resin, an acrylic resin,a melamine resin, a urethane resin, or an oxazole resin(polybenzoxazole) may also be used, or a photo-curing resin or the likecan also be used. Moreover, a dielectric constant can also be controlledby mixing these resins with microparticles having a high dielectricconstant such as barium titanate (BaTiO₃) or strontium titanate (SrTiO₃)as appropriate.

As an inorganic material used for the binder, a material selected fromsilicon oxide (SiO_(x)), silicon nitride (SiN_(x)), silicon includingoxygen and nitrogen, aluminum nitride (AlN), aluminum including oxygenand nitrogen, aluminum oxide (Al₂O₃), titanium oxide (TiO₂), BaTiO₃,SrTiO₃, lead titanate (PbTiO₃), potassium niobate (KNbO₃), lead niobate(PbNbO₃), tantalum oxide (Ta₂O₅), barium tantalate (BaTa₂O₆), lithiumtantalate (LiTaO₃), yttrium oxide (Y₂O₃), zirconium oxide (ZrO₂), zincsulfide (ZnS), and a substance including another inorganic material canbe used. By mixing the organic material with an inorganic materialhaving a high dielectric constant (by adding or the like), a dielectricconstant of a layer including a light-emitting material and alight-emitting substance formed of the binder can be further increased.

Note that although the EL element can obtain light emission when avoltage is applied between a pair of electrode layers, it is preferableto use AC drive in this embodiment mode. This is because an ELlight-emitting element shown in this embodiment mode is controlled toemit light by using an electric field generated by the first electrode201 and the second electrode 212. Note that the electric field generatedfor light emission is similar to that of each liquid crystal displaydevice described in the above-described embodiment modes.

As shown in this embodiment mode, an interval between the electrodes canbe controlled by forming the insulating film over the first electrode.For example, a micro cavity effect can also be obtain between the firstelectrode and the second electrode by controlling the interval betweenthe electrodes in the structure shown in this embodiment mode, so that alight-emitting device having excellent color purity can be manufactured.

As described above, an application range of the invention is extremelywide and the invention can be used for electronic devices in all fields.

Note that the invention is not limited to the above-described embodimentmodes, and the invention can be implemented by changing in various waysunless such changes depart from the spirit and the scope of theinvention.

Embodiment Mode 34

Electronic devices in accordance with Embodiment Mode 34 of theinvention are described with reference to FIGS. 36A to 36H. The displaydevice or the display module shown in any one of the above-describedembodiment modes is mounted in each of the electronic devices.

A camera such as a video camera or a digital camera, a goggle display (ahead mounted display), a navigation system, an audio reproducing device(e.g., a car audio component set), a computer, a game machine, aportable information terminal (e.g., a mobile computer, a mobile phone,a mobile game machine, or an electronic book), an image reproducingdevice provided with a recording medium (specifically, a device forreproducing a content of a recording medium such as a Digital VersatileDisc (DVD) and having a display which can display an reproduced image),and the like are given as these electronic devices. Specific examples ofthese electronic devices are shown in FIGS. 36A to 36H.

FIG. 36A shows a monitor of a television receiver or a personalcomputer, which includes a housing 2001, a support base 2002, a displayportion 2003, a speaker portion 2004, a video input terminal 2005, andthe like. The display device or the display module shown in any one ofthe above-described embodiment modes is used for the display portion2003. Since this display device or display module is included, degree offreedom of an interval between a common electrode and a pixel electrodeis improved. Accordingly, since optimal values for an arrangementinterval and width of an opening pattern of the pixel electrode changedepending on a distance between the pixel electrode and the commonelectrode, the size, the width, and the interval of the opening patterncan be freely set. Then, a gradient of an electric field applied betweenthe electrodes can be controlled, so that, for example, an electricfield parallel to the substrate can be easily increased. That is, sinceliquid crystal molecules which are aligned in parallel to the substrate(so-called homogeneous alignment) can be controlled in a directionparallel to the substrate in a display device using liquid crystals, aviewing angle is widened by applying an optimal electric field. Inaddition, when a part of a pixel electrode having the same potential asthat of a drain or a source of a thin film transistor is provided belowthe drain or the source of the thin film transistor, the potential ofthe drain or the source thereof is stabilized. Accordingly, since aninterval between opening patterns included in the electrodes can bereduced and an electric field is applied smoothly, liquid crystalmolecules can be easily controlled. Further, since a voltage can belowered by reducing the interval between the opening patterns includedin the electrodes, power consumption can be reduced.

FIG. 36B shows a digital camera. An image receiving portion 2103 isprovided in a front portion of a main body 2101, and a shutter button2106 is provided in a upper surface portion of the main body 2101. Inaddition, a display portion 2102, operating keys 2104, and an externalconnecting port 2105 are provided in a back portion of the main body2101. The display device or the display module shown in any one of theabove-described embodiment modes is used for the display portion 2102.Since this display device or display module is included, an advantageouseffect which is similar to that of the aforementioned embodiment modecan be obtained. For example, degree of freedom of an interval between acommon electrode and a pixel electrode is improved. Accordingly, sinceoptimal values for an arrangement interval and width of an openingpattern of the pixel electrode change depending on a distance betweenthe pixel electrode and the common electrode, the size, the width, andthe interval of the opening pattern can be freely set. Then, a gradientof an electric field applied between the electrodes can be controlled,so that, for example, an electric field parallel to the substrate can beeasily increased. That is, since liquid crystal molecules which arealigned in parallel to the substrate (so-called homogeneous alignment)can be controlled in a direction parallel to the substrate in a displaydevice using liquid crystals, a product including a liquid crystaldisplay device or a liquid crystal module having a wide viewing anglecan be provided.

FIG. 36C shows a laptop personal computer. A keyboard 2204, an externalconnecting port 2205, and a pointing device 2206 are provided in a mainbody 2201. In addition, a housing 2202 having a display portion 2203 isattached to the main body 2201. The display device or the display moduleshown in any one of the above-described embodiment modes is used for thedisplay portion 2203. Since this display device or display module isincluded, an advantageous effect which is similar to that of theaforementioned embodiment mode can be obtained. For example, degree offreedom of an interval between a common electrode and a pixel electrodeis improved. Accordingly, since optimal values for an arrangementinterval and width of an opening pattern of the pixel electrode changedepending on a distance between the pixel electrode and the commonelectrode, the size, the width, and an interval of the opening patterncan be freely set. Then, a gradient of an electric field applied betweenthe electrodes can be controlled, so that, for example, an electricfield parallel to the substrate or the like can be easily increased.That is, since liquid crystal molecules which are aligned in parallel tothe substrate (so-called homogeneous alignment) can be controlled in adirection parallel to the substrate in a display device using liquidcrystals, a product including a liquid crystal display device or aliquid crystal module having a wide viewing angle can be provided.

FIG. 36D shows a mobile computer, which includes a main body 2301, adisplay portion 2302, a switch 2303, operating keys 2304, an infraredport 2305, and the like. An active matrix display device is provided inthe display portion 2302. The display device or the display module shownin any one of the above-described embodiment modes is used for thedisplay portion 2302. Since this display device or display module isincluded, an advantageous effect which is similar to that of theaforementioned embodiment mode can be obtained. For example, degree offreedom of an interval between a common electrode and a pixel electrodeis improved. Accordingly, since optimal values for an arrangementinterval and width of an opening pattern of the pixel electrode changedepending on a distance between the pixel electrode and the commonelectrode, the size, the width, and the interval of the opening patterncan be freely set. Then, a gradient of an electric field applied betweenthe electrodes can be controlled, so that, for example, an electricfield parallel to the substrate can be easily increased. That is, sinceliquid crystal molecules which are aligned in parallel to the substrate(so-called homogeneous alignment) can be controlled in a directionparallel to the substrate in a display device using liquid crystals, aproduct including a liquid crystal display device or a liquid crystalmodule having a wide viewing angle can be provided.

FIG. 36E shows an image reproduction device. A display portion 2404, arecord medium reading portion 2405, and an operating key 2406 areprovided in a main body 2401. In addition, a housing 2402 having aspeaker portion 2407 and a display portion 2403 are attached to the mainbody 2401. The display device or the display module shown in any one ofthe above-described embodiment modes is used for each of the displayportions 2403 and 2404. Since this display device or display module isincluded, an advantageous effect which is similar to that of theaforementioned embodiment mode can be obtained. For example, degree offreedom of an interval between a common electrode and a pixel electrodeis improved. Accordingly, since optimal values for an arrangementinterval and width of an opening pattern of the pixel electrode changedepending on a distance between the pixel electrode and the commonelectrode, the size, the width, and the interval of the opening patterncan be freely set. Then, a gradient of an electric field applied betweenthe electrodes can be controlled, so that, for example, an electricfield parallel to the substrate can be easily increased. That is, sinceliquid crystal molecules which are aligned in parallel to the substrate(so-called homogeneous alignment) can be controlled in a directionparallel to the substrate in a display device using liquid crystals, aproduct including a liquid crystal display device or a liquid crystalmodule having a wide viewing angle can be provided.

FIG. 36F shows an electronic book. An operating key 2503 is provided ina main body 2501. In addition, a plurality of display portions 2502 areattached to the main body 2501. The display device or the display moduleshown in any one of the above-described embodiment modes is used for thedisplay portion 2502. Since this display device or display module isincluded, an advantageous effect which is similar to that of theaforementioned embodiment mode can be obtained. For example, degree offreedom of an interval between a common electrode and a pixel electrodeis improved. Accordingly, since optimal values for an arrangementinterval and width of an opening pattern of the pixel electrode changedepending on a distance between the pixel electrode and the commonelectrode, the size, the width, and the interval of the opening patterncan be freely set. Then, a gradient of an electric field applied betweenthe electrodes can be controlled, so that, for example, an electricfield parallel to the substrate can be easily increased. That is, sinceliquid crystal molecules which are aligned in parallel to the substrate(so-called homogeneous alignment) can be controlled in a directionparallel to the substrate in a display device using liquid crystals, aproduct including a liquid crystal display device or a liquid crystalmodule having a wide viewing angle can be provided.

FIG. 36G shows a video camera. An external connecting port 2604, aremote control receiving portion 2605, an image receiving portion 2606,a battery 2607, an audio input portion 2608, operating keys 2609, and aneye piece portion 2610 are provided in a main body 2601. In addition, ahousing 2603 having a display portion 2602 is attached to the main body2601. The display device or the display module shown in any one of theabove-described embodiment modes is used for the display portion 2602.Since this display device or display module is included, an advantageouseffect which is similar to that of the aforementioned embodiment modecan be obtained. For example, degree of freedom of an interval between acommon electrode and a pixel electrode is improved. Accordingly, sinceoptimal values for an arrangement interval and width of an openingpattern of the pixel electrode change depending on a distance betweenthe pixel electrode and the common electrode, the size, the width, andthe interval of the opening pattern can be freely set. Then, a gradientof an electric field applied between the electrodes can be controlled,so that, for example, an electric field parallel to the substrate can beeasily increased. That is, since liquid crystal molecules which arealigned in parallel to the substrate (so-called homogeneous alignment)can be controlled in a direction parallel to the substrate in a displaydevice using liquid crystals, a product including a liquid crystaldisplay device or a liquid crystal module having a wide viewing anglecan be provided.

FIG. 36H shows a mobile phone, which includes a main body 2701, ahousing 2702, a display portion 2703, an audio input portion 2704, anaudio output portion 2705, an operating key 2706, an external connectingport 2707, an antenna the 2708, and the like. The display device or thedisplay module shown in any one of the above-described embodiment modesis used for the display portion 2703. Since this display device ordisplay module is included, an advantageous effect which is similar tothat of the aforementioned embodiment mode can be obtained. For example,degree of freedom of an interval between a common electrode and a pixelelectrode is improved. Accordingly, since optimal values for anarrangement interval and width of an opening pattern of the pixelelectrode change depending on a distance between the pixel electrode andthe common electrode, the size, the width, and the interval of theopening pattern can be freely set. Then, a gradient of an electric fieldapplied between the electrodes can be controlled, so that, for example,an electric field parallel to the substrate can be easily increased.That is, since liquid crystal molecules which are aligned in parallel tothe substrate (so-called homogeneous alignment) can be controlled in adirection parallel to the substrate in a display device using liquidcrystals, a product including a liquid crystal display device or aliquid crystal module having a wide viewing angle can be provided.

This application is based on Japanese Patent Application serial No.2006-135954 filed in Japan Patent Office on May 16, 2006, the entirecontents of which are hereby incorporated by reference.

1. (canceled)
 2. A liquid crystal display device comprising: a firstgate wiring over a substrate; a first source wiring over the substrate;a semiconductor film over the first gate wiring and comprising a regionoverlapping with the first gate wiring with a gate insulating filminterposed therebetween; a conductive film over the semiconductor film;a pixel electrode over the substrate; a first insulating film over theconductive film and the pixel electrode; a second insulating film overthe first insulating film; a common electrode over the second insulatingfilm; and a liquid crystal over the common electrode, wherein theconductive film is capable of functioning as a source electrode or adrain electrode, wherein the pixel electrode comprise a region in directcontact with part of a bottom surface of the conductive film, whereinthe pixel electrode is electrically connected to the semiconductor filmthrough the conductive film, wherein the common electrode comprises aslit while the pixel electrode does not comprise a slit, and wherein, ina plan view, the common electrode comprises a region overlapping with aregion between the pixel electrode and the first source wiring.
 3. Theliquid crystal display device according to claim 2, wherein the commonelectrode does not comprise a region overlapping with a channel regionof the semiconductor film.
 4. The liquid crystal display deviceaccording to claim 2, wherein each of the pixel electrode and the commonelectrode comprises indium tin oxide.
 5. The liquid crystal displaydevice according to claim 2, wherein the conductive film comprise afirst layer comprising molybdenum, a second layer comprising molybdenum,and a third layer comprising aluminum and between the first layer andthe third layer.
 6. The liquid crystal display device according to claim2, wherein, in the plan view, the common electrode comprises a regionoverlapping with a region between the pixel electrode and the first gatewiring.
 7. A liquid crystal display device comprising: a first gatewiring over a substrate; a second gate wiring over the substrate; afirst source wiring over the substrate; a semiconductor film over thefirst gate wiring and comprising a region overlapping with the firstgate wiring with a gate insulating film interposed therebetween; aconductive film over the semiconductor film; a pixel electrode over thesubstrate; a first insulating film over the conductive film and thepixel electrode; a second insulating film over the first insulatingfilm; a common electrode over the second insulating film; and a liquidcrystal over the common electrode, wherein the second gate wiring isprovided adjacent to the first gate wiring with the pixel electrodeinterposed therebetween, wherein the conductive film is capable offunctioning as a source electrode or a drain electrode, wherein thepixel electrode comprises a region in direct contact with part of abottom surface of the conductive film, wherein the pixel electrode iselectrically connected to the semiconductor film through the conductivefilm, wherein the common electrode comprises a slit while the pixelelectrode does not comprise a slit, wherein, in a plan view, the commonelectrode comprises a region overlapping with a region between the pixelelectrode and the first source wiring, and wherein the common electrodecomprises a region overlapping with the first gate wiring and a regionoverlapping with the first gate wiring.
 8. The liquid crystal displaydevice according to claim 7, wherein the common electrode does notcomprise a region overlapping with a channel region of the semiconductorfilm.
 9. The liquid crystal display device according to claim 7, whereineach of the pixel electrode and the common electrode comprises indiumtin oxide.
 10. The liquid crystal display device according to claim 7,wherein the conductive film comprise a first layer comprisingmolybdenum, a second layer comprising molybdenum, and a third layercomprising aluminum and between the first layer and the third layer. 11.The liquid crystal display device according to claim 7, wherein, in theplan view, the common electrode comprises a region overlapping with aregion between the pixel electrode and the first gate wiring.
 12. Aliquid crystal display device comprising: a first gate wiring over asubstrate; a first source wiring over the substrate; a second sourcewiring over the substrate; a semiconductor film over the first gatewiring and comprising a region overlapping with the first gate wiringwith a gate insulating film interposed therebetween; a conductive filmover the semiconductor film; a pixel electrode over the substrate; afirst insulating film over the conductive film and the pixel electrode;a second insulating film over the first insulating film; a commonelectrode over the second insulating film; and a liquid crystal over thecommon electrode, wherein the second source wiring is provided adjacentto the first source wiring with the pixel electrode interposedtherebetween, wherein the conductive film is capable of functioning as asource electrode or a drain electrode, wherein the pixel electrodecomprises a region in direct contact with part of a bottom surface ofthe conductive film, wherein the pixel electrode is electricallyconnected to the semiconductor film through the conductive film, whereinthe common electrode comprises a slit while the pixel electrode does notcomprise a slit, wherein, in a plan view, the common electrode comprisesa region overlapping with a region between the pixel electrode and thefirst source wiring, and wherein, in the plan view, the common electrodecomprises a region overlapping with a region between the pixel electrodeand the second source wiring.
 13. The liquid crystal display deviceaccording to claim 12, wherein the common electrode does not comprise aregion overlapping with a channel region of the semiconductor film. 14.The liquid crystal display device according to claim 12, wherein each ofthe pixel electrode and the common electrode comprises indium tin oxide.15. The liquid crystal display device according to claim 12, wherein theconductive film comprise a first layer comprising molybdenum, a secondlayer comprising molybdenum, and a third layer comprising aluminum andbetween the first layer and the third layer.
 16. The liquid crystaldisplay device according to claim 12, wherein, in the plan view, thecommon electrode comprises a region overlapping with a region betweenthe pixel electrode and the first gate wiring.
 17. The display deviceaccording to claim 12, further comprising a second gate wiring over thesubstrate, wherein the second gate wiring is provided adjacent to thefirst gate wiring with the pixel electrode interposed therebetween. 18.The display device according to claim 12, wherein, in the plan view, thecommon electrode comprises a region overlapping with a region betweenthe pixel electrode and the second gate wiring.